Enum UnquoteForm 

pub enum UnquoteForm {
    Unquote,
    Splice,
}

Closed-set identifier for the syntactic marker of a macro-template unquote (,) or unquote-splice (,@). Carried as a typed slot on LispError::UnboundTemplateVar and LispError::NonSymbolUnquoteTarget so authoring tools (REPL, LSP, tatara-check) bind to variant identity via UnquoteForm::Splice rather than substring-matching the rendered prefix literal.

Mirror at the template-marker boundary of the prior-run MacroDefHead (macro-definition-head closed set), CompilerSpecIoStage (disk-persistence surface), and TemplateInvariantKind (bytecode-runtime surface) closed-set lifts: those enums key their respective rejection variants on a typed identity; this enum keys the two unquote-template rejection variants (UnboundTemplateVar, NonSymbolUnquoteTarget) on a typed marker identity. Adding a new unquote variant (e.g., a hypothetical ,~ form) requires extending this enum, which rustc-enforces matching at every projection site (marker()) — the closed set becomes a TYPE rather than two &'static str-keyed slots that could drift independently.

marker(self) -> &'static str projects the typed UnquoteForm back to the canonical literal for LispError::Display rendering. The &'static str lifetime is load-bearing: it lets both variants project through this method into their compile error in {prefix}…: prefix without an allocation, parallel to how MacroDefHead::keyword() and CompilerSpecIoStage::operation() / label() feed their respective LispError::* Display impls.

Theory anchor: THEORY.md §V.1 — knowable platform; the closed set of unquote markers becomes a TYPE rather than a runtime string-comparison-and-format dance. A typo like prefix: ",," is structurally unrepresentable rather than re-asserted at the helper boundary. THEORY.md §VI.1 — generation over composition; the typed enum lands the structural-completeness floor for the template-marker surface, parallel to how MacroDefHead lands it for the macro-definition-head surface and CompilerSpecIoStage for the disk-persistence surface. THEORY.md §II.1 invariant 1 (typed entry): a non-symbol unquote target / an unbound template var is exactly the failure mode the typed-entry gate exists to reject, and the marker identity is part of the proof.

Variants

Unquote

,x — single-value substitution. The , marker; the inner symbol is substituted with its bound value at template expansion.

Splice

,@x — list-splice substitution. The ,@ marker; the inner symbol must be bound to a list, whose elements are flattened into the containing list at template expansion.

Implementations

impl UnquoteForm

pub const ALL: [Self; 2]

The closed set of two template-marker syntactic forms — single source of truth that drives the Self::marker / [fmt::Display] projection AND the [FromStr] decode sweep keyed on Self::marker. Adding a hypothetical third variant (e.g. a ,~ reverse-unquote, a ,? conditional-unquote) lands at one Self::ALL entry + one Self::marker arm — exhaustively checked by the compiler (the [Self; 2] array literal forces the arity) AND by the per-variant truth-table tests below.

Sibling closed-set lift to every other typed-shape enum the substrate carries: this crate’s own SexpShape::ALL (the twelve reachable outer shapes — superset on the structural axis of the Sexp algebra), crate::ast::AtomKind::ALL (the six atomic-payload kinds — peer axis on the same algebra), crate::ast::QuoteForm (the four homoiconic prefix-wrappers — superset of THIS enum’s two template markers via the 2-of-4 projection crate::ast::QuoteForm::as_unquote_form), and the cross-crate tatara-process family (ConditionKind::ALL, ProcessPhase::ALL, ProcessSignal::ALL, ChannelKind::ALL, IntentKind::ALL, LifetimeKind::ALL, RequestorKind::ALL, ReceiptKind::ALL, …) every one of which paired its typed projection with ALL before this lift.

Future consumers that compose against ALL: LSP / REPL completion for the operator-facing rendered template-marker (every compile error in {prefix}…: substring in LispError’s rendered diagnostics for a template-substitution rejection keys on this set’s projection through Self::marker); tatara-check coverage assertions over which template markers reach a NonSymbolUnquoteTarget / UnboundTemplateVar arm at all — the typed sweep replaces a per-callsite vocabulary of two &'static str literals; any future audit-trail metric jointly labeled by Self::marker (e.g. tatara_lisp_unbound_template_var_total{prefix=","}) — the metric label set IS Self::ALL mapped through Self::marker; any future structural rewriter (typed analogue of MLIR’s op.walk<UnquoteFormOp>()) that wants to sweep over every template marker in a typed sequence.

pub const UNQUOTE_MARKER: &'static str = crate::ast::QuoteForm::UNQUOTE_PREFIX

Canonical &'static str template-marker bytes for the Self::Unquote substitution — aliases crate::ast::QuoteForm::UNQUOTE_PREFIX on the UnquoteForm ⊂ QuoteForm 2-of-4 subset carving so the marker-level per-role bytes bind at ONE pub const on the parent superset’s Unquote arm rather than at TWO sites (the per-role pub const AND a parallel inline literal). Per-role peer of Self::Unquote on the closed-set template-substitution algebra; consumers reach for UnquoteForm::UNQUOTE_MARKER when the caller has a variant in hand at compile time and wants the canonical diagnostic bytes without runtime dispatch through Self::marker.

Sibling posture to crate::ast::AtomKind::SYMBOL_LABEL et al (commit fc126b8) — both pin the invariant that a typed-subset enum’s per-role bytes are structurally derived from the parent superset’s per-role pub const via a pub const = Parent::CONST alias rather than through parallel literal-discipline sites.

pub const SPLICE_MARKER: &'static str = crate::ast::QuoteForm::UNQUOTE_SPLICE_PREFIX

Canonical &'static str template-marker bytes for the Self::Splice list-substitution — aliases crate::ast::QuoteForm::UNQUOTE_SPLICE_PREFIX on the UnquoteForm ⊂ QuoteForm 2-of-4 subset carving. Per-role peer of Self::Splice; the ,@ two-byte prefix is the ONLY multi-char bytes payload on the UnquoteForm algebra — every other marker is a single-byte comma rendered as &'static str.

pub const MARKERS: [&'static str; 2]

Closed-set forced-arity ALL array over the canonical template- marker &'static str bytes, in declaration order matching Self::ALL element-wise (pinned by unquote_form_markers_align_with_all_by_index). Sibling posture to crate::ast::QuoteForm::PREFIXES ([&'static str; 4] — the superset carving this UnquoteForm subset embeds into), crate::ast::AtomKind::LABELS ([&'static str; 6] — sibling subset-through-parent alias on the AtomKind ⊂ SexpShape carving), SexpShape::LABELS ([&'static str; 12]), ExpectedKwargShape::LABELS ([&'static str; 7]), KwargPathKind::LABELS ([&'static str; 3]), MacroDefHead::KEYWORDS ([&'static str; 3]), crate::ast::Atom::BOOL_LITERALS ([&'static str; 2]), and crate::macro_expand::MacroParams::LAMBDA_LIST_KEYWORDS ([&'static str; 2]) — every closed-set outer projection on the substrate that carries an &'static str-per-variant marker now pins its per-role canonical bytes at ONE pub const per role PLUS an ALL array for family-wide consumers.

Pre-lift the two template-marker bytes had NO per-role primitive on this closed-set subset algebra — a consumer with an UnquoteForm variant in hand at compile time reaching for the canonical marker bytes had to spell UnquoteForm::Splice.marker() (runtime dispatch through the composition Self::to_quote_form + crate::ast::QuoteForm::prefix) OR reach across the algebra boundary into crate::ast::QuoteForm::UNQUOTE_SPLICE_PREFIX and re-derive the UnquoteForm ⊂ QuoteForm variant pairing at the call site. Post-lift the TWO canonical bytes bind at ONE pub const per role on the typed UnquoteForm algebra AND at Self::MARKERS as a family-wide forced-arity array — a future LSP / REPL completion bar keyed on UnquoteForm::MARKERS, a tatara-check coverage sweep over the template-marker arms of a NonSymbolUnquoteTarget / UnboundTemplateVar corpus, or a Sekiban audit-trail metric jointly labeled by the template marker (tatara_lisp_unbound_template_var_total{prefix=","}) reads through the typed constants on this subset algebra without re-deriving the 2-of-4 carving inline.

Each entry is byte-for-byte identical to the corresponding crate::ast::QuoteForm Unquote / UnquoteSplice arm — an intentional cross-axis overlap pinned by unquote_form_per_role_markers_alias_quote_form_per_role_prefixes_byte_for_byte so a future marker rename on EITHER side (a crate::ast::QuoteForm "," → ",." drift, or an UnquoteForm rename that skips the alias) fails-loudly at the alias test rather than as a silent operator-facing vocabulary fracture. Adding a hypothetical third template- marker (e.g. a ,~ reverse-unquote, a ,? conditional-unquote) extends Self::ALL AND Self::MARKERS AND adds ONE per- role pub const alias in lockstep — rustc’s forced-arity check on the two [_; N] arrays fails compilation if EITHER ALL array grows without the other.

Theory anchor: THEORY.md §III — the typescape; the two canonical template-marker bytes bind at ONE typed [&'static str; 2] array on the closed-set UnquoteForm algebra rather than at zero-primitive-on-this-subset-plus-two-inline- lookups scattered across the substrate. THEORY.md §V.1 — knowable platform; the family’s cardinality becomes a TYPE- level constant on the substrate algebra rather than a per- consumer runtime dispatch through the composition. THEORY.md §VI.1 — generation over composition; the family-wide contract sweeps (alignment with ALL, pairwise disjointness, membership through Self::marker) emerge from the composition of TWO substrate primitives (this pub const array + the two per-role pub const *_MARKER aliases) rather than as per-variant inline assertions duplicated at each call site.

pub const UNQUOTE_LEAD: char = crate::ast::QuoteForm::UNQUOTE_LEAD

Canonical reader-lead char byte for BOTH Self::Unquote AND Self::Splice — aliases crate::ast::QuoteForm::UNQUOTE_LEAD (which is ',') on the UnquoteForm ⊂ QuoteForm 2-of-4 subset carving so the reader-lead-char per-role bytes bind at ONE pub const on the parent superset’s Unquote arm rather than at TWO sites (the per-role pub const AND a parallel inline ',' literal). Per-role peer of Self::Unquote on the closed-set template-substitution algebra; consumers reach for UnquoteForm::UNQUOTE_LEAD when the caller has a variant in hand at compile time and wants the canonical reader-entry lead char without runtime dispatch through self.to_quote_form().lead_char().

The (2-of-2 collapse) shape-asymmetry is load-bearing: BOTH UnquoteForm arms share the SAME lead char at crate::ast::QuoteForm::lead_char’s Self::Unquote | Self::UnquoteSplice => Self::UNQUOTE_LEAD merged arm — the reader’s outer tokenizer dispatch selects between quote-family entry and every non-quote-family arm on lead char alone, with the ,-vs-,@ disambiguation falling out of the reader’s second-char peek (@ promotes to Splice) rather than at crate::ast::QuoteForm::from_lead_char’s decode. This UnquoteForm ⊂ QuoteForm subset’s LEAD alias is SHAPE-ASYMMETRIC-COLLAPSE to [Self::UNQUOTE_LEAD] (a single-entry ALL — see Self::LEADS) because both subset arms project to the same superset lead byte, mirroring the parent’s [QUOTE_LEAD, QUASIQUOTE_LEAD, UNQUOTE_LEAD] shape- asymmetric collapse (3 distinct leads for 4 arms).

Sibling posture to Self::UNQUOTE_MARKER (commit 3640f76 — aliases the reader-punctuation prefix vocabulary ","), Self::UNQUOTE_LABEL (commit da68af5 — aliases the substrate diagnostic-label vocabulary "unquote"), Self::UNQUOTE_IAC_FORGE_TAG (commit 6acab84 — aliases the iac-forge canonical-form vocabulary "unquote"), and Self::UNQUOTE_HASH_DISCRIMINATOR (commit eca4730 — aliases the outer-Sexp cache-key u8 byte 5u8) — this FIFTH per-role pub const axis closes the (reader-lead char, reader-prefix bytes, diagnostic label, iac-forge canonical-form tag, outer-Sexp cache-key byte) QUINTUPLE on the UnquoteForm subset algebra in lockstep with the same quintuple on the parent crate::ast::QuoteForm superset.

pub const LEADS: [char; 1]

Closed-set forced-arity ALL array over the canonical reader-lead char bytes on the UnquoteForm ⊂ QuoteForm 2-of-4 subset carving — SHAPE-ASYMMETRIC-COLLAPSE [char; 1] on this subset carving (both arms share the same ',' lead byte), peer to crate::ast::QuoteForm::LEADS ([char; 3] on the 4-arm superset carving, itself shape-asymmetric-collapse from 4 arms to 3 distinct leads because crate::ast::QuoteForm::Unquote and crate::ast::QuoteForm::UnquoteSplice share the same lead byte).

Peer axis to Self::MARKERS on the SAME reader-vocabulary production surface: Self::MARKERS holds the arm-per-arm prefix bytes (",", ",@" — cardinality matches Self::ALL at [_; 2]), and Self::LEADS holds the DISTINCT lead-byte sub-vocabulary the reader’s outer tokenizer dispatch selects on ("," alone — cardinality collapses from 2 arms to 1 distinct lead byte). The shape-asymmetric arities [_; 2] for MARKERS vs [_; 1] for LEADS ARE the shared-lead-char structural collapse invariant carried at the type-system level — a future third UnquoteForm arm (e.g. a hypothetical ,~ reverse-unquote binding a NEW lead char ~) would extend BOTH Self::MARKERS to [_; 3] AND Self::LEADS to [_; 2] in lockstep, adding ONE per-role LEAD pub const alias.

Sibling posture to crate::ast::QuoteForm::LEADS (the superset carving’s own DISTINCT-lead-byte ALL array on the SAME reader-lead-vocabulary axis), Self::MARKERS, Self::LABELS, Self::IAC_FORGE_TAGS, and Self::HASH_DISCRIMINATORS — every one a forced-arity ALL array on the SAME UnquoteForm closed-set algebra spanning ONE of the production byte-vocabularies the substrate carries per role.

Pre-lift the sole distinct lead byte had NO per-role primitive on this closed-set subset algebra — a consumer wanting the UnquoteForm-only reader-lead-byte set had to spell the two- step composition UnquoteForm::ALL.iter().map(|uf| uf.to_quote_form().lead_char()).collect() (with a manual dedup downstream to project the 2-arm output onto its 1 distinct byte) OR reach across into crate::ast::QuoteForm::UNQUOTE_LEAD and re-derive the UnquoteForm ⊂ QuoteForm variant-share pairing at the call site. Post-lift the sole canonical byte binds at ONE pub const on the typed UnquoteForm algebra AND at Self::LEADS as a family-wide [char; 1] forced-arity array — a future substrate-facing reader-classifier keyed on the substitution- subset’s lead-vocabulary specifically (a future LSP completion bar filtering to template-substitution-only entries, a syntax-highlighter’s per-char classifier for the reader-entry template-marker subset, a tatara-check predicate (check-substitution-subset-lead-partition …) that verifies the subset’s sole lead byte sits inside the parent crate::ast::QuoteForm::LEADS set) reads through the typed constants without re-deriving the 2-of-4 → 1-of-3 collapse inline.

Theory anchor: THEORY.md §III — the typescape; the sole canonical distinct-lead byte on the substitution-subset carving binds at ONE typed [char; 1] array on the closed-set UnquoteForm algebra rather than as a zero-primitive-on-this- subset-plus-inline-lookup at each callsite. Closes the FIFTH per-role pub const axis on the UnquoteForm subset carving in lockstep with the same quintuple on crate::ast::QuoteForm. THEORY.md §V.1 — knowable platform; the SHAPE-ASYMMETRIC- COLLAPSE distinct-lead-byte sub-vocabulary becomes load-bearing typed data on the substrate’s substitution-subset closed set — the type-system carries the “both subset arms share ONE lead” invariant at the [char; 1] arity rather than as a comment on a lookup site. THEORY.md §VI.1 — generation over composition; the family-wide contract sweeps (alignment with the parent crate::ast::QuoteForm::LEADS’s subset image, cardinality containment Self::LEADS.len() <= Self::ALL.len() — the collapse witness) emerge from ONE substrate primitive plus the per-role LEAD alias rather than from per-consumer runtime dispatch through the two-step composition.

pub const UNQUOTE_IAC_FORGE_TAG: &'static str = crate::ast::QuoteForm::UNQUOTE_IAC_FORGE_TAG

Canonical &'static str iac-forge canonical-form tag bytes for the Self::Unquote substitution — aliases crate::ast::QuoteForm::UNQUOTE_IAC_FORGE_TAG on the UnquoteForm ⊂ QuoteForm 2-of-4 subset carving so the iac-forge-tag-level per-role bytes bind at ONE pub const on the parent superset’s Unquote arm rather than at TWO sites (the per-role pub const AND a parallel inline literal). Per-role peer of Self::Unquote on the closed-set template- substitution algebra; consumers reach for UnquoteForm::UNQUOTE_IAC_FORGE_TAG when the caller has a variant in hand at compile time and wants the canonical iac- forge interop-tag bytes without runtime dispatch through Self::iac_forge_tag.

Sibling posture to Self::UNQUOTE_MARKER (commit 3640f76) — both pin the invariant that a typed-subset enum’s per-role bytes are structurally derived from the parent superset’s per-role pub const via a pub const = Parent::CONST alias rather than through parallel literal-discipline sites. Where Self::UNQUOTE_MARKER aliases the reader-punctuation vocabulary (",") shared with the Lisp source-code surface, this constant aliases the iac-forge canonical-form vocabulary ("unquote") shared with the cross-crate attestation surface — the two peer axes span the two production byte-vocabularies the parent crate::ast::QuoteForm closed set carries, and both now bind through the same aliased typed source of truth on this UnquoteForm subset.

pub const SPLICE_IAC_FORGE_TAG: &'static str = crate::ast::QuoteForm::UNQUOTE_SPLICE_IAC_FORGE_TAG

Canonical &'static str iac-forge canonical-form tag bytes for the Self::Splice list-substitution — aliases crate::ast::QuoteForm::UNQUOTE_SPLICE_IAC_FORGE_TAG on the UnquoteForm ⊂ QuoteForm 2-of-4 subset carving. Per-role peer of Self::Splice; the "unquote-splicing" bytes are the ONLY hyphenated multi-syllable canonical-form tag on the UnquoteForm algebra — the other iac-forge tag is a single word.

INTENTIONALLY diverges from crate::error::SexpShape::label’s splice arm (which renders "unquote-splice" for the diagnostic surface) — the iac-forge canonical-form REQUIRES the unquote-splicing spelling, while the substrate’s operator- facing diagnostic surface renders the shorter idiom. The typed per-role pub const documents the divergence structurally: a future “consolidation” PR that homogenizes the two axes would have to touch this constant explicitly, surfacing the boundary- distinct invariant at code-review time rather than silently.

pub const IAC_FORGE_TAGS: [&'static str; 2]

Closed-set forced-arity ALL array over the canonical iac-forge canonical-form tag &'static str bytes, in declaration order matching Self::ALL element-wise (pinned by unquote_form_iac_forge_tags_align_with_all_by_index). Sibling posture to Self::MARKERS ([&'static str; 2] on the reader- punctuation axis of the SAME UnquoteForm closed set — commit 3640f76) and to crate::ast::QuoteForm::IAC_FORGE_TAGS ([&'static str; 4] — the superset carving this UnquoteForm subset embeds into on the SAME iac-forge canonical-form axis). The (canonical iac-forge tag) axis + the (canonical reader marker) axis together span the two production byte-vocabularies the UnquoteForm closed set carries — Self::MARKERS holds the Lisp source-code prefixes (",", ",@") the reader tokenizes on, Self::IAC_FORGE_TAGS holds the cross-crate canonical-form tag strings ("unquote", "unquote-splicing") the iac-forge interop layer round-trips through.

Pre-lift the two iac-forge tag bytes had NO per-role primitive on this closed-set subset algebra — a consumer with an UnquoteForm variant in hand at compile time reaching for the canonical tag bytes had to spell UnquoteForm::Splice.iac_forge_tag() (runtime dispatch through the composition Self::to_quote_form + crate::ast::QuoteForm::iac_forge_tag) OR reach across the algebra boundary into crate::ast::QuoteForm::UNQUOTE_SPLICE_IAC_FORGE_TAG and re-derive the UnquoteForm ⊂ QuoteForm variant pairing at the call site. Post-lift the TWO canonical bytes bind at ONE pub const per role on the typed UnquoteForm algebra AND at Self::IAC_FORGE_TAGS as a family-wide forced-arity array — a future LSP / REPL completion bar keyed on UnquoteForm::IAC_FORGE_TAGS, a tatara-check coverage sweep over the template-marker arms of an attestation-payload corpus, or a Sekiban audit-trail metric jointly labeled by the iac- forge tag (tatara_lisp_iac_forge_tag_total{tag="unquote"}) reads through the typed constants on this subset algebra without re-deriving the 2-of-4 carving inline.

Each entry is byte-for-byte identical to the corresponding crate::ast::QuoteForm Unquote / UnquoteSplice arm — an intentional cross-axis overlap pinned by unquote_form_per_role_iac_forge_tags_alias_quote_form_per_role_iac_forge_tags_byte_for_byte so a future canonical-form tag rename on EITHER side (a crate::ast::QuoteForm "unquote" → "unquote-value" drift, or an UnquoteForm rename that skips the alias) fails-loudly at the alias test rather than as a silent cross-crate canonical-form vocabulary fracture that mis-hashes BLAKE3 attestation keys. Adding a hypothetical third template-marker (e.g. a ,~ reverse-unquote with its own canonical "reverse- unquote" tag, a ,? conditional-unquote with its own tag) extends Self::ALL AND Self::IAC_FORGE_TAGS AND adds ONE per-role pub const alias in lockstep — rustc’s forced-arity check on the two [_; N] arrays fails compilation if EITHER ALL array grows without the other.

Theory anchor: THEORY.md §III — the typescape; the two canonical iac-forge tag bytes bind at ONE typed [&'static str; 2] array on the closed-set UnquoteForm algebra rather than at zero-primitive-on-this-subset-plus-two-inline- lookups scattered across the substrate. THEORY.md §V.1 — knowable platform; the family’s cardinality becomes a TYPE- level constant on the substrate algebra rather than a per- consumer runtime dispatch through the composition. THEORY.md §V.3 — three-pillar attestation; the canonical iac-forge tag bytes are the surface the substrate’s cross-crate intent_hash pillar composes over for every substitution-subset arm of a homoiconic template AST — binding the two bytes on the typed algebra makes attestation-key drift a compile error rather than a silent BLAKE3 mis-hash. THEORY.md §VI.1 — generation over composition; the family-wide contract sweeps (alignment with ALL, pairwise disjointness, membership through Self::iac_forge_tag) emerge from the composition of TWO substrate primitives (this pub const array + the two per-role pub const *_IAC_FORGE_TAG aliases) rather than as per-variant inline assertions duplicated at each call site.

pub const UNQUOTE_LABEL: &'static str = crate::ast::QuoteForm::UNQUOTE_LABEL

Canonical &'static str diagnostic label bytes for the Self::Unquote substitution — aliases crate::ast::QuoteForm::UNQUOTE_LABEL on the UnquoteForm ⊂ QuoteForm 2-of-4 subset carving so the label-level per-role bytes bind at ONE pub const on the parent superset’s Unquote arm (which itself aliases SexpShape::UNQUOTE_LABEL on the QuoteForm ⊂ SexpShape 4-of-12 subset carving) rather than at multiple sites (the per-role pub const PLUS a parallel inline literal). Per-role peer of Self::Unquote on the closed-set template-substitution algebra; consumers reach for UnquoteForm::UNQUOTE_LABEL when the caller has a variant in hand at compile time and wants the canonical diagnostic bytes without runtime dispatch through Self::label.

Sibling posture to Self::UNQUOTE_MARKER (commit 3640f76 — aliases the reader-punctuation vocabulary ",") and to Self::UNQUOTE_IAC_FORGE_TAG (commit 6acab84 — aliases the iac-forge canonical-form vocabulary "unquote") — this THIRD per-role pub const axis closes the (reader punctuation, diagnostic label, iac-forge canonical-form) triple on the UnquoteForm subset algebra in lockstep with the same triple on the parent crate::ast::QuoteForm superset. At the Unquote arm the diagnostic label AND the iac-forge tag AND the substrate-facing SexpShape::UNQUOTE_LABEL all agree byte-for-byte on "unquote"; the divergence axis lives at Self::SPLICE_LABEL ("unquote-splice") vs Self::SPLICE_IAC_FORGE_TAG ("unquote-splicing").

pub const SPLICE_LABEL: &'static str = crate::ast::QuoteForm::UNQUOTE_SPLICE_LABEL

Canonical &'static str diagnostic label bytes for the Self::Splice list-substitution — aliases crate::ast::QuoteForm::UNQUOTE_SPLICE_LABEL on the UnquoteForm ⊂ QuoteForm 2-of-4 subset carving. Per-role peer of Self::Splice. The "unquote-splice" short label matches SexpShape::UNQUOTE_SPLICE_LABEL byte-for-byte through the alias chain and diverges INTENTIONALLY from Self::SPLICE_IAC_FORGE_TAG ("unquote-splicing") — the two projections key the SAME closed set on TWO distinct boundaries (substrate diagnostic surface vs cross-crate Common-Lisp canonical form). See Self::UNQUOTE_LABEL for the alias- chain shape both siblings share.

pub const LABELS: [&'static str; 2]

Closed-set forced-arity ALL array over the canonical diagnostic label &'static str bytes, in declaration order matching Self::ALL element-wise (pinned by unquote_form_labels_align_with_all_by_index). Sibling posture to Self::MARKERS ([&'static str; 2] — reader-punctuation axis) and Self::IAC_FORGE_TAGS ([&'static str; 2] — iac- forge canonical-form axis) on the SAME UnquoteForm closed set, and to crate::ast::QuoteForm::LABELS ([&'static str; 4] — the superset carving this UnquoteForm subset embeds into on the SAME diagnostic-label axis). The (diagnostic label) axis + the (reader punctuation) axis + the (iac-forge canonical-form) axis together span the THREE production byte-vocabularies the UnquoteForm closed set carries — Self::MARKERS holds the Lisp source-code prefixes (",", ",@"), Self::LABELS holds the substrate diagnostic labels ("unquote", "unquote-splice"), Self::IAC_FORGE_TAGS holds the cross- crate canonical-form tag strings ("unquote", "unquote- splicing").

Pre-lift the two diagnostic-label bytes had NO per-role primitive on this closed-set subset algebra — a consumer with an UnquoteForm variant in hand at compile time reaching for the canonical diagnostic bytes had to spell the two-step composition uf.to_quote_form().label() OR reach across the algebra boundary into crate::ast::QuoteForm::UNQUOTE_SPLICE_LABEL and re-derive the UnquoteForm ⊂ QuoteForm variant pairing at the call site. Post-lift the TWO canonical bytes bind at ONE pub const per role on the typed UnquoteForm algebra AND at Self::LABELS as a family-wide forced-arity array — a future LSP / REPL completion bar keyed on UnquoteForm::LABELS, a tatara-check coverage sweep over the template-marker arms of a diagnostic corpus, or a Sekiban audit-trail metric jointly labeled by the diagnostic label (tatara_lisp_unbound_template_var_total{label="unquote"}) reads through the typed constants on this subset algebra without re-deriving the 2-of-4 carving inline.

Each entry is byte-for-byte identical to the corresponding crate::ast::QuoteForm Unquote / UnquoteSplice arm — an intentional cross-axis overlap pinned by unquote_form_per_role_labels_alias_quote_form_per_role_labels_byte_for_byte so a future label rename on EITHER side (a crate::ast::QuoteForm "unquote" → "substitute" drift, or an UnquoteForm rename that skips the alias) fails- loudly at the alias test rather than as a silent operator- facing vocabulary fracture. Adding a hypothetical third template-marker (e.g. a ,~ reverse-unquote) extends Self::ALL AND Self::LABELS AND adds ONE per-role pub const alias in lockstep — rustc’s forced-arity check on the two [_; N] arrays fails compilation if EITHER array grows without the other.

Theory anchor: THEORY.md §III — the typescape; the two canonical diagnostic label bytes bind at ONE typed [&'static str; 2] array on the closed-set UnquoteForm algebra rather than at zero-primitive-on-this-subset-plus-two-inline- lookups scattered across the substrate. Closes the THIRD per-role pub const axis on the UnquoteForm subset carving in lockstep with the same triple on crate::ast::QuoteForm. THEORY.md §V.1 — knowable platform; the family’s cardinality becomes a TYPE-level constant on the substrate algebra rather than a per-consumer runtime dispatch through the composition. THEORY.md §VI.1 — generation over composition; the family-wide contract sweeps (alignment with ALL, pairwise disjointness, membership through Self::label) emerge from the composition of TWO substrate primitives (this pub const array + the two per-role pub const *_LABEL aliases) rather than as per- variant inline assertions duplicated at each call site. THEORY.md §II.1 invariant 5 — composition preserves proofs; the alias-chain composition law UnquoteForm::LABELS[i] == UnquoteForm::ALL[i].to_quote_form().label() binds the family- wide array to the composition through Self::to_quote_form + crate::ast::QuoteForm::label at rustc time.

pub const UNQUOTE_SHAPE: SexpShape = crate::ast::QuoteForm::UNQUOTE_SHAPE

Canonical SexpShape embed target for the Self::Unquote template-substitution arm on the UnquoteForm ⊂ QuoteForm ⊂ SexpShape composed carving — aliases crate::ast::QuoteForm::UNQUOTE_SHAPE on the parent’s 4-of-12 quote-family carving byte-for-byte (which in turn aliases SexpShape::Unquote). Per-role peer of Self::Unquote on the closed-set UnquoteForm ⊂ SexpShape 2-of-12 composed embed axis; consumers with an UnquoteForm variant in hand at compile time bind the canonical embed target through ONE typed pub const on the subset algebra rather than through runtime dispatch via Self::sexp_shape OR by reaching across the two-hop Self::to_quote_form().sexp_shape() composition OR by re-deriving the UnquoteForm ⊂ QuoteForm ⊂ SexpShape variant pairing inline. Sibling posture to Self::UNQUOTE_MARKER on the reader-prefix axis, Self::UNQUOTE_LEAD on the reader-lead axis, Self::UNQUOTE_IAC_FORGE_TAG on the iac-forge canonical-form tag axis, Self::UNQUOTE_LABEL on the diagnostic-label axis, and Self::UNQUOTE_HASH_DISCRIMINATOR on the outer-Sexp cache-key byte axis — every one of the pre-existing per-role sub-vocabulary aliases on this subset algebra now has a peer per-role SexpShape embed-target alias on the SAME closed-set UnquoteForm ⊂ QuoteForm 2-of-4 subset carving.

pub const SPLICE_SHAPE: SexpShape = crate::ast::QuoteForm::UNQUOTE_SPLICE_SHAPE

Canonical SexpShape embed target for the Self::Splice template-substitution arm on the UnquoteForm ⊂ QuoteForm ⊂ SexpShape composed carving — aliases crate::ast::QuoteForm::UNQUOTE_SPLICE_SHAPE on the parent’s 4-of-12 quote-family carving byte-for-byte (which in turn aliases SexpShape::UnquoteSplice). Per-role peer of Self::Splice on the closed-set UnquoteForm ⊂ SexpShape 2-of-12 composed embed axis. See Self::UNQUOTE_SHAPE for the alias-chain shape every sibling shares.

pub const SHAPES: [SexpShape; 2]

Closed-set forced-arity ALL array over the canonical SexpShape embed targets on the UnquoteForm ⊂ SexpShape 2-of-12 composed carving, in declaration order matching Self::ALL element-wise (pinned by unquote_form_shapes_align_with_all_by_index). Sibling posture to Self::MARKERS ([&'static str; 2] — reader-prefix bytes), Self::LEADS ([char; 1] — SHAPE-ASYMMETRIC-COLLAPSE distinct- lead byte), Self::IAC_FORGE_TAGS ([&'static str; 2] — iac- forge canonical-form tags), Self::LABELS ([&'static str; 2] — diagnostic labels), Self::HASH_DISCRIMINATORS ([u8; 2] — outer-Sexp cache-key bytes), and Self::PROMOTIONS ([(Self, char, Self); 1] — SHAPE-ASYMMETRIC-COLLAPSE promotion triples) on the SAME closed-set UnquoteForm algebra; where those six arrays lift per-role sub-vocabularies on the substitution subset algebra, this array lifts the per-role SexpShape embed-target sub-vocabulary at the same [_; 2] forced arity.

Aliased through crate::ast::QuoteForm::UNQUOTE_SHAPE + crate::ast::QuoteForm::UNQUOTE_SPLICE_SHAPE via the per-role Self::UNQUOTE_SHAPE + Self::SPLICE_SHAPE constants — the UnquoteForm ⊂ QuoteForm 2-of-4 subset carving of the parent’s 4-of-12 quote-family SHAPES. Sibling posture to crate::ast::QuoteForm::SHAPES ([SexpShape; 4]) — the parent superset’s peer array on the QuoteForm ⊂ SexpShape 4-of-12 carving; together with the three closed-set carvings’ arrays (crate::ast::AtomKind::SHAPES 6-of-12, crate::ast::QuoteForm::SHAPES 4-of-12, StructuralKind::SHAPES 2-of-12) the four SHAPES arrays now close the FULL twelve-arm outer-shape algebra uniformly PLUS the UnquoteForm 2-of-4 subset carving of the quote-family sub- algebra.

Pre-lift the two SexpShape embed targets had NO per-role primitive on this subset algebra — a consumer with an UnquoteForm variant in hand at compile time reaching for the canonical embed target had to spell UnquoteForm::Unquote.sexp_shape() (runtime dispatch through Self::sexp_shape’s two-hop .to_quote_form().sexp_shape() composition) OR reach across into crate::ast::QuoteForm::UNQUOTE_SHAPE and re-derive the UnquoteForm ⊂ QuoteForm 2-of-4 subset pairing at the call site. Post-lift the TWO canonical embed targets bind at ONE pub const per role on the typed UnquoteForm subset algebra AND at Self::SHAPES as a family-wide forced-arity array — a future LSP / REPL completion bar keyed on UnquoteForm::SHAPES for the “which SexpShape does this UnquoteForm embed into?” outer-shape column, a tatara-check coverage sweep zipping UnquoteForm::ALL / LABELS / MARKERS / LEADS / IAC_FORGE_TAGS / HASH_DISCRIMINATORS / PROMOTIONS / SHAPES in lockstep for a family-wide (variant, label, marker, lead, iac-forge tag, cache-key byte, promotion triple, embed- target) octuple render, or a Sekiban audit-trail metric jointly labeled by the embed target’s SexpShape identity reads through the typed constants on this subset algebra without re-deriving the 2-of-12 composed carving inline.

Round-trip identity with the inverse projection SexpShape::as_unquote_form: for every index i, Self::SHAPES[i].as_unquote_form() == Some(Self::ALL[i]) (pinned by unquote_form_shapes_align_with_all_by_index_through_as_unquote_form) — the embed / project section closes as a family-wide array- indexed law on the composed 2-of-12 carving rather than as a per-variant assertion sweep. Adding a hypothetical third template-substitution marker (e.g. ,~ reverse-unquote for destructuring-bind hygiene, ,? conditional-unquote) extends Self::ALL AND Self::SHAPES AND crate::ast::QuoteForm::ALL AND crate::ast::QuoteForm::SHAPES AND SexpShape::ALL AND adds ONE per-role pub const *_SHAPE in lockstep — rustc’s forced- arity check on the two [_; N] arrays fails compilation if EITHER ALL array grows without the other, AND the peer SexpShape::as_unquote_form arm must grow in lockstep to preserve the round-trip identity.

Theory anchor: THEORY.md §III — the typescape; the two canonical SexpShape embed targets bind at ONE typed [SexpShape; 2] array on the closed-set UnquoteForm subset algebra rather than at zero-primitive-on-this-subset-plus-two-inline-lookups-through- two-hop-composition scattered across the substrate. THEORY.md §II.1 invariant 2 — free middle; the (embed, project) pair binds at THREE typed sites now — the projection method Self::sexp_shape, this family-wide array, AND the peer inverse SexpShape::as_unquote_form — with rustc-enforced consistency across all three via the array-indexed round-trip law. THEORY.md §V.1 — knowable platform; the family’s cardinality becomes a TYPE-level constant on the substrate algebra rather than a per- consumer runtime dispatch through the two-hop composition. THEORY.md §VI.1 — generation over composition; the family-wide contract sweeps (alignment with ALL, round-trip through as_unquote_form, membership through sexp_shape, pairwise injectivity across the two embed targets, alias byte-equality with QuoteForm’s per-role SHAPE constants) emerge from the composition of TWO substrate primitives (this pub const array + the two per-role pub const *_SHAPE aliases) rather than as per-variant inline assertions duplicated at each call site.

pub fn marker(self) -> &'static str

Project the typed UnquoteForm to the canonical &'static str literal — feeds the LispError::UnboundTemplateVar / LispError::NonSymbolUnquoteTarget Display rendering via the #[error(...)] annotation. The &'static str lifetime is load-bearing: it lets the variants project through this method into their compile error in {prefix}…: prefix without an allocation, parallel to how MacroDefHead::keyword() and CompilerSpecIoStage::operation() / label() feed their respective LispError::* Display impls.

Composition law: self.marker() == self.to_quote_form().prefix() for every self: UnquoteForm. Pre-lift the body inlined the two literals ("," / ",@") as a parallel match-table; the same two literals also lived at the matching Unquote/UnquoteSplice arms of crate::ast::QuoteForm::prefix. Post-lift the body composes Self::to_quote_form() (the typed 2-of-4 subset → superset projection) with crate::ast::QuoteForm::prefix() (the canonical 4-of-4 prefix-string projection), so the two &'static str literals live at ONE canonical site (QuoteForm::prefix’s Unquote/UnquoteSplice arms in ast.rs) and every consumer of UnquoteForm::marker (the ClosedSet-trait Display/FromStr surface via #[closed_set(via = "marker")], the unbound-template did you mean ,@args? hint suffix in this module’s unbound_hint_suffix helper, the #[error("... {prefix}")] annotation on LispError::UnboundTemplateVar / LispError::NonSymbolUnquoteTarget, the future LSP / REPL / tatara-check completion-bar projections that key on the typed marker) inherits the canonical vocabulary through the composition rather than through a parallel inline table that drifts at the next vocabulary rename.

Sibling-shape lift to the prior-run AtomKind::label ⊂ SexpShape::label composition (commit 1db697f): both pin the invariant that a typed-subset enum’s projection on a closed-set vocabulary is structurally derived from its parent superset’s projection, not a parallel literal table the type system happens to not catch when the vocabularies drift.

The bidirectional contract is anchored by tests: unquote_form_marker_projects_canonical_literal_for_each_variant pins each variant’s canonical literal so a typo in any arm fails-loudly, unquote_form_display_renders_canonical_marker_for_each_variant pins Display-equals-marker so any #[error("... {prefix}")] annotation that threads through this projection projects byte-for-byte, unquote_form_marker_round_trips_through_from_str pins the marker ↔ [Self::FromStr] round-trip for every variant in Self::ALL so the typed surface and the rendered diagnostic literal cannot drift, and the post-lift composition-routing pin unquote_form_marker_routes_through_to_quote_form_prefix_via_composition asserts pointer-equality between self.marker() and self.to_quote_form().prefix() for every variant — so a regression that re-inlines the literals as a parallel match-table fails the pointer pin even when the rendered bytes still agree (the inline-literal-table copy lives at a different &'static str address).

pub fn to_quote_form(self) -> QuoteForm

Project the 2-of-4 template-substitution subset back to its parent crate::ast::QuoteForm superset — the structural inverse of crate::ast::QuoteForm::as_unquote_form. Returns the crate::ast::QuoteForm variant whose canonical prefix string matches this UnquoteForm’s marker: Self::Unquote → crate::ast::QuoteForm::Unquote, Self::Splice → crate::ast::QuoteForm::UnquoteSplice.

Total (not Option) because every UnquoteForm IS a QuoteForm — the 2-of-4 subset is a subset by inclusion. The dual projection crate::ast::QuoteForm::as_unquote_form returns Option<UnquoteForm> because the two non-substitution variants (crate::ast::QuoteForm::Quote and crate::ast::QuoteForm::Quasiquote) lie outside the substitution subset.

Round-trip identity: self.to_quote_form().as_unquote_form() == Some(self) for every self: UnquoteForm, pinned by unquote_form_to_quote_form_round_trips_through_as_unquote_form. The dual identity qf.as_unquote_form().map(|uf| uf.to_quote_form()) == qf.as_unquote_form().map(|_| qf) holds by construction (the projection is a section of crate::ast::QuoteForm::as_unquote_form restricted to its image — the Unquote/UnquoteSplice variants).

Lifts the (UnquoteForm variant, QuoteForm variant) pairing onto the typed algebra so consumers that need the parent superset from a substitution-subset value (the marker lift’s composition root, the future hint-suffix pretty-printer’s prefix.to_quote_form().prefix() routing, the future canonical-form interop tag that wants to route an UnquoteForm through iac_forge_tag via to_quote_form().iac_forge_tag() without re-deriving the pairing — now closed at Self::iac_forge_tag) bind at ONE typed projection rather than at parallel match arms each site re-derives.

Theory anchor: THEORY.md §V.1 — knowable platform; the subset-to-superset projection becomes a TYPE projection on the substrate algebra. THEORY.md §VI.1 — generation over composition; the (UnquoteForm variant, QuoteForm variant) pairing emerges from this ONE primitive rather than from per-callsite per-variant literals. THEORY.md §II.1 invariant 1 — typed entry; the typed subset-to-superset projection IS a substrate-owned theorem rather than a hand-inlined match-table duplication discipline N sites had to keep in lockstep.

pub fn wrap(self, inner: Sexp) -> Sexp

Project the 2-of-4 template-substitution subset marker back into its matching crate::ast::Sexp wrapper variant applied to inner — the typed-CONSTRUCT face on the closed-set UnquoteForm algebra, sibling section-for-retraction of the existing typed- PROJECT face crate::ast::Sexp::as_unquote on the outer crate::ast::Sexp algebra. Self::Unquote yields crate::ast::Sexp::Unquote, Self::Splice yields crate::ast::Sexp::UnquoteSplice, each boxing inner into the corresponding tuple-variant constructor (fn(Box<Sexp>) -> Sexp).

Closes the (construct, project) algebra dual on the closed-set UnquoteForm algebra — the substitution-subset peer of the closed-set superset algebra’s already-closed dual pair (crate::ast::QuoteForm::wrap + crate::ast::Sexp::as_quote_form). Where the superset’s wrap reaches all four homoiconic prefix-wrappers and its projection returns Option<(QuoteForm, &Sexp)> on the outer crate::ast::Sexp algebra, this subset’s wrap reaches only the two template-substitution wrappers (crate::ast::Sexp::Unquote and crate::ast::Sexp::UnquoteSplice) and its projection sibling crate::ast::Sexp::as_unquote returns Option<(UnquoteForm, &Sexp)> — the (construct, project) pair on the subset algebra is symmetric with the (construct, project) pair on the superset algebra, each closed at one method per direction on the respective closed set.

Composition law (forward): self.wrap(inner) == self.to_quote_form().wrap(inner) for every self: UnquoteForm and every inner: Sexp — routes through the superset’s crate::ast::QuoteForm::wrap at the single tuple-variant emission site so the (marker, Sexp::* tuple-variant constructor) pairing binds at ONE closed-set match on the superset algebra rather than at a parallel two-arm match table on this subset. Round-trip law (section-for-retraction with the soft-projection sibling): self.wrap(inner).as_unquote() == Some((self, &inner)) for every self: UnquoteForm and every inner: Sexp — the subset’s typed constructor pairs section-for-retraction with the outer algebra’s soft projection, and the marker + inner body cross-projection preserves identity on the substitution-subset closed set. Sibling-shape lift to the prior-run UnquoteForm::marker ⊂ QuoteForm::prefix composition (commit 250c001): both pin the invariant that a typed-subset enum’s projection on a closed-set operation is structurally derived from its parent superset’s projection through the canonical to_quote_form composition, not a parallel inline match-table the type system happens to not catch when the vocabularies drift.

Pre-lift consumers that had an UnquoteForm marker in hand and wanted to build a fresh crate::ast::Sexp wrapper had to spell the two-step composition uf.to_quote_form().wrap(inner) — a future template rewriter consuming crate::ast::Sexp::as_unquote’s Option<(UnquoteForm, &Sexp)> projection and threading a rewritten inner body back into the matching wrapper on the substitution-subset closed set (a future TypedRewriter<UnquoteFormOp> sweep, a future macro-template canonicalizer that normalizes ,x / ,@x shapes, a future REPL pretty-printer that emits a fresh substitution wrapper from a borrowed marker + inner pair) would have re-derived the .to_quote_form().wrap(_) composition at every callsite. Post- lift the composition binds at ONE typed-algebra method on the closed-set UnquoteForm algebra, matching the section-for- retraction posture the superset’s crate::ast::QuoteForm::wrap already carries on the outer crate::ast::Sexp algebra. The (marker, Sexp::* tuple-variant constructor) pairing continues to live at ONE site on the superset’s wrap closed-set match (the single tuple-variant emission point the substrate owns), which is what this subset method routes through — no parallel match table, no per-arm drift risk on the two-variant closed set.

The crate::ast::Sexp (owned) return type complements crate::ast::Sexp::as_unquote’s &Sexp (borrowed) — symmetric with the (crate::ast::QuoteForm::wrap, crate::ast::Sexp::as_quote_form) asymmetry on the superset algebra: wrap consumes the inner body to build the new wrapper, the projection borrows the inner body from the existing wrapper. The typed Box::new(inner) allocation lives at ONE site on the superset’s crate::ast::QuoteForm::wrap (the closed-set tuple-variant emission point), so a future allocation-policy change (e.g. arena-allocated wrappers for span-aware crate::ast::Sexp) lands as ONE edit at the superset’s wrap and propagates through this subset method byte-for-byte.

Theory anchor: THEORY.md §II.1 invariant 1 — typed entry; the (UnquoteForm variant, Sexp::* tuple-variant constructor) pairing binds at ONE typed-algebra method on the subset algebra, routed through the ONE closed-set match on the superset algebra the substrate already owns. THEORY.md §II.1 invariant 2 — free middle; every consumer that has an UnquoteForm marker and wants to build a wrapper Sexp routes through the SAME typed method, so a regression that drifts one consumer’s pairing from the others cannot reach the substrate’s runtime. THEORY.md §V.1 — knowable platform; the typed-construct face becomes a TYPE projection on the subset algebra sitting next to the typed- project face crate::ast::Sexp::as_unquote on the outer crate::ast::Sexp algebra rather than a bare to_quote_form().wrap(_) two-step composition consumers had to re-derive per site. THEORY.md §VI.1 — generation over composition; the (subset marker, wrapper Sexp) pairing emerges from ONE typed-algebra composition on the subset algebra rather than from parallel per-consumer per-variant literals.

Frontier inspiration: Racket’s syntax/parse ~or* (~unquote stx) (~unquote-splice stx) pattern paired one-for-one with a typed constructor face on the same subset shape — the (project, construct) algebra dual is closed at one method per direction on Racket’s substitution-subset surface, and UnquoteForm::wrap / crate::ast::Sexp::as_unquote is the Rust-typed peer on the closed-set UnquoteForm algebra with crate::ast::QuoteForm::wrap standing in for Racket’s typed dispatch through the superset. MLIR’s typed factory mlir::OpBuilder::create<UnquoteFamilyOp>(loc, inner) paired with the projection sibling mlir::dyn_cast<UnquoteFamilyOp>(op) — the typed factory + typed downcast pair the IR algebra closes over on every wrapper op subset; UnquoteForm::wrap / crate::ast::Sexp::as_unquote is the unstructured-Rust peer on the outer crate::ast::Sexp algebra with the closed-set UnquoteForm standing in for MLIR’s subset-of-OperationName taxonomy over the substitution-subset op family.

pub fn sexp_shape(self) -> SexpShape

Project the 2-of-4 template-substitution subset marker into its matching SexpShape variant on the outer crate::ast::Sexp algebra’s twelve-variant shape lattice — Self::Unquote → SexpShape::Unquote, Self::Splice → SexpShape::UnquoteSplice. Section peer of SexpShape::as_unquote_form on the 2-of-12 carving that names the template-substitution wrappers; closes the (embed, project) algebra dual on the UnquoteForm ⊂ SexpShape typed-shape lattice, sibling of the already-closed (crate::ast::AtomKind::sexp_shape, SexpShape::as_atom_kind) dual on the 6-of-12 atomic-payload carving AND (crate::ast::QuoteForm::sexp_shape, SexpShape::as_quote_form) dual on the 4-of-12 quote-family carving.

Composition law: self.sexp_shape() == self.to_quote_form().sexp_shape() for every self: UnquoteForm. The (subset marker, outer SexpShape) pairing binds at ONE closed-set match on the superset’s crate::ast::QuoteForm::sexp_shape rather than at a parallel two-arm inline match table on this subset — matching the posture Self::marker takes through crate::ast::QuoteForm::prefix and Self::wrap takes through crate::ast::QuoteForm::wrap. Round-trip law (section-for-retraction with the outer projection sibling): self.sexp_shape().as_unquote_form() == Some(self) for every self: UnquoteForm.

Pre-lift the (UnquoteForm variant, SexpShape variant) pairing had NO typed projection on this subset algebra — a template rewriter with an UnquoteForm marker in hand wanting the outer SexpShape identity (e.g., a future tatara-check predicate that filters diagnostics to “this rejection was on a template- substitution wrapper”, a future LSP hover that renders a typed marker’s outer-shape witness alongside its punctuation, a future macro-hygiene analyzer that keys on the outer shape of a captured substitution point) had to spell the two-step composition uf.to_quote_form().sexp_shape() at every callsite. Post-lift the composition binds at ONE typed-algebra method on the closed- set UnquoteForm algebra, and the (embed, project) pair with SexpShape::as_unquote_form forms an Iso(UnquoteForm, UnquoteShape ⊂ SexpShape) on the substitution-subset carving.

Theory anchor: THEORY.md §V.1 — knowable platform; the (subset marker, outer shape) pairing becomes a TYPE projection on the substrate algebra rather than a per-callsite .to_quote_form() .sexp_shape() two-step. THEORY.md §II.1 invariant 2 — free middle; every consumer that has an UnquoteForm marker and wants the outer SexpShape routes through the SAME typed method. THEORY.md §VI.1 — generation over composition; the pairing emerges from ONE typed-algebra composition on the subset algebra rather than from parallel per-consumer per-variant literals.

Frontier inspiration: MLIR’s mlir::OperationName typed projection from a subset-op-family value into the parent OperationName taxonomy — the (subset op, taxonomic identity) pairing lives at ONE typed projection on the subset algebra, composed through the parent op-family’s typed identity face. UnquoteForm::sexp_shape is the Rust-typed peer on the closed- set UnquoteForm algebra with SexpShape standing in for MLIR’s parent OperationName taxonomy.

pub fn iac_forge_tag(self) -> &'static str

Project the 2-of-4 template-substitution subset marker into its canonical iac-forge interop tag — Self::Unquote → "unquote", Self::Splice → "unquote-splicing". The Common-Lisp-canonical tag string crate::ast::QuoteForm::iac_forge_tag projects on the superset carving, restricted through Self::to_quote_form to the substitution-subset carving.

Composition law: self.iac_forge_tag() == self.to_quote_form().iac_forge_tag() for every self: UnquoteForm. The body composes Self::to_quote_form (the typed 2-of-4 subset → superset projection) with crate::ast::QuoteForm::iac_forge_tag (the canonical 4-of-4 interop-tag projection), so the two &'static str literals live at ONE canonical site (QuoteForm::iac_forge_tag’s Unquote/UnquoteSplice arms in ast.rs) — the (subset marker, canonical iac-forge tag string) pairing binds at ONE closed-set match on the superset algebra rather than at a parallel two-arm inline match table on this subset. Matches the posture Self::marker takes through crate::ast::QuoteForm::prefix, Self::wrap takes through crate::ast::QuoteForm::wrap, and Self::sexp_shape takes through crate::ast::QuoteForm::sexp_shape — the FOURTH composition-through-to_quote_form axis the closed-set subset algebra closes.

The &'static str lifetime is load-bearing: every future iac- forge consumer with an UnquoteForm marker in hand projects through this method into the canonical 2-element-list head without an allocation, parallel to how Self::marker projects the reader-punctuation vocabulary. The tag stays intentionally disjoint from Self::marker (reader punctuation: "," / ",@") AND from Self::sexp_shape’s crate::error::SexpShape::label rendering (diagnostic label: "unquote" / "unquote-splice") at the substitution-subset’s Splice arm — the CL canonical form REQUIRES the unquote-splicing spelling, while the substrate’s diagnostic surface renders unquote-splice. The two projections key the SAME closed-set on TWO distinct boundaries; consolidating them would silently break either the iac-forge canonical-form round- trip OR the operator-facing diagnostic surface. That distinction is pinned bit-for-bit through the composition law: this method AGREES with crate::ast::QuoteForm::iac_forge_tag at every variant AND disagrees with crate::error::SexpShape::label at the Splice arm through the same closed-set typed algebra.

Pre-lift the (UnquoteForm variant, iac-forge tag) pairing had NO typed projection on this subset algebra — a future consumer with an UnquoteForm marker wanting the canonical iac-forge tag (e.g. a future template rewriter emitting canonical-form diagnostics keyed on the substitution-subset marker, a future tatara-check predicate that renders (check-iac-forge-tag ,x) for a substitution-subset value, a future audit-trail metric jointly labeled by the interop tag on a template- substitution rejection) had to spell the two-step composition uf.to_quote_form().iac_forge_tag() at every callsite — exactly the composition the docstring for Self::wrap explicitly names as the NEXT deferred sweep this lift picks up. Post-lift the composition binds at ONE typed-algebra method on the closed-set UnquoteForm algebra sitting next to the three prior sibling projections (Self::marker, Self::wrap, Self::sexp_shape), closing the FOURTH composition-through-to_quote_form axis on the subset — every substrate-surface axis the superset algebra carries (crate::ast::QuoteForm::prefix, crate::ast::QuoteForm::wrap, crate::ast::QuoteForm::sexp_shape, crate::ast::QuoteForm::iac_forge_tag) now has a matching composition on the substitution subset.

Theory anchor: THEORY.md §V.1 — knowable platform; the (subset marker, canonical iac-forge tag) pairing becomes a TYPE projection on the substrate algebra rather than a per-callsite .to_quote_form().iac_forge_tag() two-step. THEORY.md §II.1 invariant 2 — free middle; every consumer that has an UnquoteForm marker and wants the canonical iac-forge tag routes through the SAME typed method. THEORY.md §VI.1 — generation over composition; the pairing emerges from ONE typed-algebra composition on the subset algebra rather than from parallel per-consumer per-variant literals. A future third template-substitution marker (e.g. ,~ reverse-unquote) extends Self::ALL + Self::to_quote_form’s dispatch table in lockstep — rustc-enforced through the closed-set exhaustiveness — with THIS method inheriting the extension through the crate::ast::QuoteForm::iac_forge_tag composition site without a per-site edit.

Frontier inspiration: Racket’s syntax-source-module + syntax->datum interop chain paired with a substitution-subset pattern-class projection — the (subset pattern, canonical interop identity) pairing lives at ONE typed projection on the subset algebra, composed through the parent syntactic-form interop identity face. UnquoteForm::iac_forge_tag is the Rust-typed peer on the closed-set UnquoteForm algebra with crate::ast::QuoteForm::iac_forge_tag standing in for Racket’s parent syntactic-form interop identity taxonomy. MLIR’s mlir::OperationName::getStringRef() typed projection from a subset-op-family value into the canonical cross-crate op-identity string — the (subset op, canonical string) pairing lives at ONE typed projection on the subset algebra, composed through the parent op-family’s typed identity face. UnquoteForm::iac_forge_tag is the Rust-typed peer on the closed-set UnquoteForm algebra with iac_forge_tag standing in for MLIR’s getStringRef cross-boundary identity face.

pub fn label(self) -> &'static str

Project the 2-of-4 template-substitution subset marker into its canonical substrate diagnostic label — Self::Unquote → "unquote", Self::Splice → "unquote-splice". Feeds the same SexpShape::label-backed diagnostic surface consumers reach for on the parent crate::ast::QuoteForm::label projection, restricted through Self::to_quote_form to the substitution-subset carving.

Composition law: self.label() == self.to_quote_form().label() for every self: UnquoteForm. The body composes Self::to_quote_form (the typed 2-of-4 subset → superset projection) with crate::ast::QuoteForm::label (the canonical 4-of-4 diagnostic-label projection through crate::ast::QuoteForm::sexp_shape + SexpShape::label), so the two &'static str literals live at ONE canonical site (SexpShape::UNQUOTE_LABEL / SexpShape::UNQUOTE_SPLICE_LABEL in error.rs) — the (subset marker, canonical diagnostic label) pairing binds at ONE closed-set match on the superset algebra rather than at a parallel two-arm inline match table on this subset. Matches the posture Self::marker takes through crate::ast::QuoteForm::prefix, Self::wrap takes through crate::ast::QuoteForm::wrap, Self::sexp_shape takes through crate::ast::QuoteForm::sexp_shape, and Self::iac_forge_tag takes through crate::ast::QuoteForm::iac_forge_tag — the FIFTH composition-through-to_quote_form axis the closed-set subset algebra closes.

The &'static str lifetime is load-bearing: every future diagnostic consumer with an UnquoteForm marker in hand projects through this method into the canonical SexpShape-label vocabulary without an allocation, parallel to how Self::marker projects the reader-punctuation vocabulary and Self::iac_forge_tag projects the cross-crate iac-forge vocabulary. The diagnostic label stays intentionally distinct from Self::marker (reader punctuation: "," / ",@") AND diverges INTENTIONALLY from Self::iac_forge_tag at the Splice arm — label renders "unquote-splice" (substrate diagnostic surface) while iac_forge_tag renders "unquote- splicing" (Common-Lisp canonical form). The typed method documents the boundary-distinct invariant structurally: a future “consolidation” that homogenizes the two axes would have to touch this method explicitly.

Note: #[closed_set(via = "marker")] on the enum’s derive wires the trait-side tatara_closed_set::ClosedSet::label projection to Self::marker (the reader-punctuation byte), NOT to this inherent label (which is the SexpShape-diagnostic label). The inherent surface takes precedence for direct uf.label() calls; generic consumers reaching through the trait (<UnquoteForm as ClosedSet>::label(uf)) still see the marker. This mirrors crate::ast::QuoteForm::label’s posture on the parent superset (crate::ast::QuoteForm’s trait label is wired via #[closed_set(via = "prefix")] to prefix, while its inherent label returns sexp_shape().label()) — the UnquoteForm subset now closes the SAME (inherent-diagnostic, trait-punctuation) split on its subset algebra.

Theory anchor: THEORY.md §V.1 — knowable platform; the (subset marker, canonical diagnostic label) pairing becomes a TYPE projection on the substrate algebra rather than a per- callsite .to_quote_form().label() two-step. THEORY.md §II.1 invariant 2 — free middle; every consumer that has an UnquoteForm marker and wants the canonical diagnostic label routes through the SAME typed method. THEORY.md §VI.1 — generation over composition; the pairing emerges from ONE typed-algebra composition on the subset algebra rather than from parallel per-consumer per-variant literals. A future third template-substitution marker (e.g. ,~ reverse-unquote) extends Self::ALL + Self::to_quote_form’s dispatch table in lockstep — rustc-enforced through the closed-set exhaustiveness — with THIS method inheriting the extension through the crate::ast::QuoteForm::label composition site without a per-site edit.

Trait Implementations

impl Clone for UnquoteForm

fn clone(&self) -> UnquoteForm

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl ClosedSet for UnquoteForm

const ALL: &'static [Self]

The closed set — every variant the enum carries, in declaration order. Implementors typically delegate to an inherent pub const ALL: [Self; N] whose forced-arity array literal pins the cardinality at the declaration site.

const SET_LABEL: &'static str = "unquote form"

The substrate-wide spaced-lowercase NAME of the closed set — the noun phrase the parse-rejection diagnostic threads into "unknown {SET_LABEL}: {input}" and the typed companion the trait exposes to generic consumers (metrics taggers, REPL / LSP completion bars, exhaustive-listing renderers) that want to name the set without re-deriving the projection at every call site.

type Unknown = UnknownUnquoteForm

The typed parse-rejection carrier this implementor emits when Self::parse_label is handed a non-canonical input. The substrate-wide convention is the pub struct UnknownX(pub String) shape with a #[error("unknown <thing>: {0}")] annotation, but the trait does not require either — implementors are free to use a richer carrier (a sum type, a structured diagnostic) as long as it remains the FromStr::Err for the implementing type.

fn label(self) -> &'static str

Project the typed variant to its canonical &'static str label — the projection Self::parse_label keys on.

fn make_unknown(s: &str) -> Self::Unknown

Wrap the offending input verbatim in the typed parse-rejection carrier — the substrate-wide convention is Self::Unknown(s.to_owned()) for the pub struct UnknownX(pub String) shape. The &str borrow (rather than String) lets implementors that want to project the input through a normalization step (a future structured diagnostic carrier that records both the raw and the normalized form) do so without forcing the trait surface to materialize an owned String the implementor doesn’t need.

const CARDINALITY: usize = _

The closed set’s cardinality — the count of variants in Self::ALL, surfaced as a compile-time-known usize on the trait so downstream generic code can bind to it in const contexts ([T; N] dimensions, Vec::with_capacity sizing, bitset widths, per-variant lookup-table shapes) without re-deriving Self::ALL.len() at every call site.

fn parse_label(s: &str) -> Result<Self, Self::Unknown>

Decode a canonical Self::label back into the typed variant — Ok(v) when s matches some v.label() exactly, and Err(Self::make_unknown(s)) for every other string.

fn find_by_label(s: &str) -> Option<Self>

Zero-allocation typed decode — Some(v) when s matches some variant’s Self::label exactly, None for every other string.

fn contains_label(s: &str) -> bool

Pure-membership predicate — true iff s matches some variant’s Self::label exactly, false for every other string.

fn labels() -> Vec<&'static str>

Collect every variant’s canonical Self::label into a freshly-allocated Vec<&'static str> — Self::ALL’s elements projected through Self::label, in declaration order.

fn labels_joined(sep: &str) -> String

Render the closed set’s canonical labels joined by sep — the substrate-wide candidate-list-as-string shape consumers thread into structured-rejection diagnostics (expected one of: nix/flux/lisp/container/aplicacao/guest, allowed: :name, :threshold, targets are kustomization|helm-release|deployment).

fn sorted_labels() -> Vec<&'static str>

Project Self::labels into ASCII-sort_unstable lexicographic order — the substrate-wide canonical candidate-list ordering every per-implementor _all_is_unique_and_complete test inlines a hand-rolled let mut sorted: Vec<&str> = T::ALL.iter().map(label) .collect(); sorted.sort_unstable(); triple to materialize.

fn sorted_labels_joined(sep: &str) -> String

Render the closed set’s canonical labels in ASCII-sort_unstable lexicographic order, joined by sep — the substrate-wide canonical-ordered candidate-list-as-string shape consumers thread into structured-rejection diagnostics that want alphabetized rendering (expected one of: aplicacao/container/flux/guest/lisp/nix, LSP completion bars sorted for humans, tatara-check “did you mean X?” hints that walk a byte-wise-sorted candidate table).

fn sorted_variants() -> Vec<Self>

Collect every typed variant into a freshly-allocated Vec<Self> ordered by ASCII lexicographic Self::label — the typed-variant sibling of Self::sorted_labels on the (typed variant, canonical label) axis of the closed-set candidate-listing surface.

fn sorted_indices() -> Vec<usize>

The lex-order full-set decl-index list — the Vec<usize> decl-slot projection of Self::sorted_variants over the closed-set full-set lex-axis aggregation surface. Every entry i in the returned vector is the Self::index_of declaration-slot of some variant in Self::sorted_variants; the returned vector’s entries are ORDERED by lex position but each entry carries the DECLARATION slot the variant sits at in Self::ALL, not the lex slot. Equivalently: the returned vector is a PERMUTATION of 0..T::CARDINALITY — every declaration slot appears exactly once (paired with clause 96 in assert_closed_set_well_formed) — and reading the permutation left-to-right walks the closed set in ASCII-sort_unstable label order.

fn suggest_closest(needle: &str) -> Option<Self>

Project needle onto the closest variant whose Self::label sits within the substrate-wide bounded edit distance — the typed bridge between an unrecognized input and the “did you mean …?” diagnostic surface.

fn parse_label_with_hint(s: &str) -> Result<Self, (Self::Unknown, Option<Self>)>

Decode s into the typed variant, threading a typed Self::suggest_closest hint into the rejection envelope — the structured-diagnostic surface that composes Self::parse_label + Self::suggest_closest into ONE call a downstream LSP / tatara-check consumer takes as T: ClosedSet.

fn find_by_label_with_hint(s: &str) -> Result<Self, Option<Self>>

Zero-allocation typed decode of s, threading a typed Self::suggest_closest hint into the rejection envelope — the structured-diagnostic surface that composes Self::find_by_label + Self::suggest_closest into ONE call a downstream LSP / config-decoder / filter-map consumer takes as T: ClosedSet WITHOUT paying the Self::make_unknown carrier allocation Self::parse_label_with_hint threads on rejection.

fn index_of(self) -> usize

Project self onto its zero-indexed position in Self::ALL — the reverse projection of the Self::ALL slice’s array-index surface. Closes the (variant → position, position → variant) bijection with 0..Self::CARDINALITY that every per-variant lookup-table / bitset / compact-encoding consumer binds to.

fn from_index(i: usize) -> Option<Self>

Recover the typed variant at declaration-order position i in Self::ALL, or None if i >= Self::CARDINALITY.

fn first() -> Self

The declaration-order first variant of the closed set — Self::ALL[0] projected onto the trait surface as a panic-free typed anchor. Closes the (endpoint = 0) corner of the closed-set endpoint-anchor axis.

fn last() -> Self

The declaration-order last variant of the closed set — Self::ALL[Self::ALL.len() - 1] projected onto the trait surface as a panic-free typed anchor. Closes the (endpoint = CARDINALITY - 1) corner of the closed-set endpoint-anchor axis.

fn first_label() -> &'static str

The declaration-order head-endpoint label — T::first().label() projected onto the trait surface as ONE call. Closes the (Self, &'static str) return-type axis on the declaration- axis (head, tail) endpoint-anchor partition at the head slot.

fn last_label() -> &'static str

The declaration-order tail-endpoint label — T::last().label() projected onto the trait surface as ONE call. Closes the (Self, &'static str) return-type axis on the declaration- axis (head, tail) endpoint-anchor partition at the tail slot.

fn first_index() -> usize

The declaration-order head-endpoint DECL-INDEX — T::first().index_of() projected onto the trait surface as ONE call. Opens the usize-typed return-type column on the declaration-axis (head, tail) endpoint-anchor singular partition at the head slot, mirroring Self::first_label one return-type axis over on the (&'static str, usize) return-shape column of the declaration-axis singular endpoint-anchor projection matrix.

fn last_index() -> usize

The declaration-order tail-endpoint DECL-INDEX — T::last().index_of() projected onto the trait surface as ONE call. Closes the (usize, tail) corner of the (return-type × endpoint-direction) 3×2 declaration-axis singular endpoint-anchor return-shape matrix alongside Self::first (Self, head), Self::last (Self, tail), Self::first_label (&'static str, head), Self::last_label (&'static str, tail), and its head-direction sibling Self::first_index (usize, head).

fn is_first_label(s: &str) -> bool

The declaration-order head-endpoint LABEL predicate — true iff s equals Self::first_label, false otherwise. Closes the (arg-type × endpoint-direction) 2×2 declaration-axis endpoint-membership matrix at the (&str, head) corner alongside Self::is_first (Self, head), Self::is_last (Self, tail), and its tail-direction sibling Self::is_last_label (&str, tail).

fn is_last_label(s: &str) -> bool

The declaration-order tail-endpoint LABEL predicate — true iff s equals Self::last_label, false otherwise. Closes the (&str, tail) corner of the (arg-type × endpoint-direction) 2×2 declaration-axis endpoint-membership matrix alongside Self::is_first (Self, head), Self::is_last (Self, tail), and Self::is_first_label (&str, head), completing the (arg-type × endpoint-direction) 2×2 declaration-axis label-and-variant endpoint-membership square.

fn is_first(self) -> bool

The declaration-order head-endpoint membership predicate — true when self is Self::first, false otherwise. Closes the (endpoint-anchor Self-returning, endpoint-membership bool-returning) return-type axis over the (head, tail) partition of the declaration-axis endpoint surface.

fn is_last(self) -> bool

The declaration-order tail-endpoint membership predicate — true when self is Self::last, false otherwise. Closes the (bool, tail) corner of the (return-type × endpoint-direction) 2×2 declaration-axis endpoint matrix alongside Self::is_first.

fn is_first_index(i: usize) -> bool

The declaration-order head-endpoint INDEX predicate — true iff the usize argument equals 0 (the declaration-order head-endpoint’s array slot in Self::ALL), false otherwise. Closes the (usize, head) corner of the (arg-type × endpoint-direction) 3×2 declaration-axis endpoint-membership matrix alongside Self::is_first (Self, head), Self::is_last (Self, tail), Self::is_first_label (&str, head), and Self::is_last_label (&str, tail).

fn is_last_index(i: usize) -> bool

The declaration-order tail-endpoint INDEX predicate — true iff the usize argument equals T::CARDINALITY - 1 (the declaration-order tail-endpoint’s array slot in Self::ALL), false otherwise. Closes the (usize, tail) corner of the (arg-type × endpoint-direction) 3×2 declaration-axis endpoint-membership matrix alongside Self::is_first (Self, head), Self::is_last (Self, tail), Self::is_first_label (&str, head), Self::is_last_label (&str, tail), and its head-direction sibling Self::is_first_index (usize, head), completing the (arg-type × endpoint-direction) 3×2 declaration-axis index-and-label-and-variant endpoint-membership rectangle.

fn is_sorted_first_index(i: usize) -> bool

The lexicographic-order head-endpoint INDEX predicate — true iff the usize argument equals 0 (the lex-order head- endpoint’s slot in Self::sorted_variants, where the argument is interpreted as a LEX position — the natural output shape of Self::sorted_index_of, Self::sorted_next_index, Self::sorted_prev_index, Self::cycle_sorted_next_index, and Self::cycle_sorted_prev_index), false otherwise. Closes the (usize, lex, head) corner of the (arg-type × ordering × endpoint-direction) 3×2×2 = 12-corner endpoint- membership hypercube alongside Self::is_first (Self, declaration, head), Self::is_last (Self, declaration, tail), Self::is_sorted_first (Self, lex, head), Self::is_sorted_last (Self, lex, tail), Self::is_first_label (&str, declaration, head), Self::is_last_label (&str, declaration, tail), Self::is_sorted_first_label (&str, lex, head), Self::is_sorted_last_label (&str, lex, tail), Self::is_first_index (usize, declaration, head), and Self::is_last_index (usize, declaration, tail).

fn is_sorted_last_index(i: usize) -> bool

The lexicographic-order tail-endpoint INDEX predicate — true iff the usize argument equals T::CARDINALITY - 1 (the lex- order tail-endpoint’s slot in Self::sorted_variants, where the argument is interpreted as a LEX position — the natural output shape of Self::sorted_index_of, Self::sorted_next_index, Self::sorted_prev_index, Self::cycle_sorted_next_index, and Self::cycle_sorted_prev_index), false otherwise. Closes the (usize, lex, tail) corner of the (arg-type × ordering × endpoint-direction) 3×2×2 = 12-corner endpoint-membership hypercube — the TWELFTH and final corner alongside the eleven enumerated in Self::is_sorted_first_index’s docstring.

fn sorted_first() -> Self

The lexicographically-least variant of the closed set — the canonical minimum-by-Self::label under the standard-library str: Ord ordering, projected onto the trait surface as a panic-free typed anchor. Closes the (lexicographic-order, head) corner of the (ordering-axis × endpoint-direction) 2×2 endpoint-anchor matrix — sibling posture to Self::first (declaration-order, head), Self::last (declaration-order, tail), and Self::sorted_last (lexicographic-order, tail).

fn sorted_last() -> Self

The lexicographically-greatest variant of the closed set — the canonical maximum-by-Self::label under the standard-library str: Ord ordering, projected onto the trait surface as a panic-free typed anchor. Closes the (lexicographic-order, tail) corner of the (ordering-axis × endpoint-direction) 2×2 endpoint-anchor matrix.

fn sorted_first_label() -> &'static str

The lex-order head-endpoint label — T::sorted_first().label() projected onto the trait surface as ONE call. Closes the (Self, &'static str) return-type axis on the lex-axis (head, tail) endpoint-anchor partition at the head slot, completing the (declaration × lex) × (head, tail) × (Self-anchor, label) 2×2×2 = 8-corner endpoint-anchor return-shape cube alongside Self::first / Self::last / Self::sorted_first / Self::sorted_last (the Self-anchor corners), Self::first_label / Self::last_label (the declaration-axis label corners), and Self::sorted_last_label (the lex tail-label corner).

fn sorted_last_label() -> &'static str

The lex-order tail-endpoint label — T::sorted_last().label() projected onto the trait surface as ONE call. Closes the (Self, &'static str) return-type axis on the lex-axis (head, tail) endpoint-anchor partition at the tail slot, completing the (declaration × lex) × (head, tail) × (Self-anchor, label) 2×2×2 = 8-corner endpoint-anchor return-shape cube.

fn sorted_first_index() -> usize

The lex-order head-endpoint DECL-INDEX — T::sorted_first().index_of() projected onto the trait surface as ONE call. Opens the usize-typed return-type row on the lex-axis (head, tail) singular endpoint-anchor return-shape column at the head slot, mirroring Self::sorted_first_label one return-type axis over on the (&'static str, usize) return-shape column of the lex-axis singular endpoint-anchor projection matrix AND mirroring Self::first_index one ordering axis over on the (declaration, lex) partition of the closed-set singular head- endpoint decl-slot return-shape column.

fn sorted_last_index() -> usize

The lex-order tail-endpoint DECL-INDEX — T::sorted_last().index_of() projected onto the trait surface as ONE call. Closes the (usize, lex, tail) corner of the (return-type × ordering × endpoint-direction) 3×2×2 = 12-corner singular endpoint-anchor return-shape hypercube alongside the other eleven corners: Self::first / Self::last / Self::sorted_first / Self::sorted_last on the Self-anchor row, Self::first_label / Self::last_label / Self::sorted_first_label / Self::sorted_last_label on the label row, and Self::first_index / Self::last_index / Self::sorted_first_index (this method’s head sibling) on the decl-slot row.

fn is_sorted_first(self) -> bool

The lexicographic-order head-endpoint membership predicate — true when self is Self::sorted_first, false otherwise. Closes the (lex, head) corner of the (ordering-axis × endpoint- direction) 2×2 endpoint-membership matrix alongside Self::is_first (declaration, head), Self::is_last (declaration, tail), and Self::is_sorted_last (lex, tail).

fn is_sorted_last(self) -> bool

The lexicographic-order tail-endpoint membership predicate — true when self is Self::sorted_last, false otherwise. Closes the (lex, tail) corner of the (ordering-axis × endpoint- direction) 2×2 endpoint-membership matrix, completing the (return-type × ordering × direction) 2×2×2 = 8-corner endpoint cube alongside Self::is_first, Self::is_last, and Self::is_sorted_first.

fn is_sorted_first_label(s: &str) -> bool

The lexicographic-order head-endpoint LABEL predicate — true iff s equals Self::sorted_first_label, false otherwise. Closes the (&str, lex, head) corner of the (arg-type × ordering × endpoint-direction) 2×2×2 = 8-corner endpoint-membership hypercube alongside Self::is_first (Self, declaration, head), Self::is_last (Self, declaration, tail), Self::is_sorted_first (Self, lex, head), Self::is_sorted_last (Self, lex, tail), Self::is_first_label (&str, declaration, head), and Self::is_last_label (&str, declaration, tail).

fn is_sorted_last_label(s: &str) -> bool

The lexicographic-order tail-endpoint LABEL predicate — true iff s equals Self::sorted_last_label, false otherwise. Closes the (&str, lex, tail) corner of the (arg-type × ordering × endpoint-direction) 2×2×2 = 8-corner endpoint- membership hypercube alongside Self::is_first (Self, declaration, head), Self::is_last (Self, declaration, tail), Self::is_sorted_first (Self, lex, head), Self::is_sorted_last (Self, lex, tail), Self::is_first_label (&str, declaration, head), Self::is_last_label (&str, declaration, tail), and Self::is_sorted_first_label (&str, lex, head), completing the 8-corner hypercube on the closed-set endpoint-membership surface.

fn is_endpoint(self) -> bool

The declaration-order endpoint-membership predicate — true when self is either Self::first or Self::last, false on every strictly-interior slot. The endpoint-partition arm of the (endpoint, interior) boolean-partition axis over the declaration-axis endpoint surface — one predicate-flavor axis over from the point-membership pair (Self::is_first, Self::is_last) and the natural complement of Self::is_interior.

fn is_interior(self) -> bool

The declaration-order interior-membership predicate — true when self is neither Self::first nor Self::last, false on both endpoints. The natural complement of Self::is_endpoint on the (endpoint, interior) boolean- partition axis over the declaration-axis endpoint surface.

fn is_sorted_endpoint(self) -> bool

The lexicographic-order endpoint-membership predicate — true when self is either Self::sorted_first or Self::sorted_last, false on every strictly-interior lex slot. The endpoint-partition arm of the (endpoint, interior) boolean-partition axis over the LEX-axis endpoint surface — one predicate-flavor axis over from the lex point-membership pair (Self::is_sorted_first, Self::is_sorted_last) and the natural complement of Self::is_sorted_interior.

fn is_sorted_interior(self) -> bool

The lexicographic-order interior-membership predicate — true when self is neither Self::sorted_first nor Self::sorted_last, false on both lex endpoints. The natural complement of Self::is_sorted_endpoint on the (endpoint, interior) boolean-partition axis over the LEX-axis endpoint surface.

fn is_endpoint_label(s: &str) -> bool

The declaration-order label-shaped endpoint-membership predicate — true iff s equals Self::first_label OR Self::last_label, false on every strictly-interior canonical label AND on every non- canonical input. Closes the (&str, declaration, endpoint) corner of the (arg-type × ordering × predicate-flavor) 2×2×2 = 8-corner boolean-boundary hypercube alongside Self::is_endpoint (Self, declaration, endpoint), Self::is_interior (Self, declaration, interior), Self::is_sorted_endpoint (Self, lex, endpoint), and Self::is_sorted_interior (Self, lex, interior), opening the label-shaped column on the boolean-boundary surface one arg-type axis over from the pre-existing Self-arg (endpoint, interior) partition.

fn is_interior_label(s: &str) -> bool

The declaration-order label-shaped interior-membership predicate — true iff s is a canonical label of a strictly-interior variant (neither Self::first_label nor Self::last_label), false on both endpoint labels AND on every non-canonical input. Closes the (&str, declaration, interior) corner of the (arg-type × ordering × predicate-flavor) 2×2×2 = 8-corner boolean-boundary hypercube alongside Self::is_endpoint_label (&str, declaration, endpoint).

fn is_sorted_endpoint_label(s: &str) -> bool

The lexicographic-order label-shaped endpoint-membership predicate — true iff s equals Self::sorted_first_label OR Self::sorted_last_label, false on every strictly-lex- interior canonical label AND on every non-canonical input. Closes the (&str, lex, endpoint) corner of the (arg-type × ordering × predicate-flavor) 2×2×2 = 8-corner boolean-boundary hypercube alongside Self::is_endpoint_label (&str, declaration, endpoint) and Self::is_sorted_endpoint (Self, lex, endpoint).

fn is_sorted_interior_label(s: &str) -> bool

The lexicographic-order label-shaped interior-membership predicate — true iff s is a canonical label of a strictly- lex-interior variant, false on both lex-endpoint labels AND on every non-canonical input. Closes the (&str, lex, interior) corner and the final corner of the (arg-type × ordering × predicate-flavor) 2×2×2 = 8-corner boolean-boundary hypercube alongside Self::is_sorted_endpoint_label (&str, lex, endpoint), Self::is_endpoint_label (&str, declaration, endpoint), Self::is_interior_label (&str, declaration, interior), Self::is_endpoint / Self::is_interior on the declaration Self-arg column, and Self::is_sorted_endpoint / Self::is_sorted_interior on the lex Self-arg column.

fn is_endpoint_index(i: usize) -> bool

The declaration-order index-shaped endpoint-membership predicate — true iff the usize argument equals 0 (the declaration-order head-endpoint’s slot in Self::ALL) OR T::CARDINALITY - 1 (the declaration-order tail-endpoint’s slot), false on every strictly-interior slot AND on every out-of-range usize. Opens the usize-arg column of the (arg-type × ordering × predicate-flavor × endpoint-direction) hyperbook at the (declaration, endpoint) corner alongside the pre-existing Self-arg column (Self::is_endpoint, Self::is_interior, Self::is_sorted_endpoint, Self::is_sorted_interior) and &str-arg column (Self::is_endpoint_label, Self::is_interior_label, Self::is_sorted_endpoint_label, Self::is_sorted_interior_label).

fn is_interior_index(i: usize) -> bool

The declaration-order index-shaped interior-membership predicate — true iff i names the array slot of a strictly-interior variant (neither the declaration-order head slot 0 nor the declaration-order tail slot T::CARDINALITY - 1), false on both endpoint slots AND on every out-of-range usize. Closes the (usize, declaration, interior) corner of the (arg-type × ordering × predicate-flavor) 3×2×2 = 12-corner boolean-boundary hypercube alongside Self::is_endpoint_index (usize, declaration, endpoint) and the pre-existing eight Self-and- &str corners.

fn is_sorted_endpoint_index(i: usize) -> bool

The lexicographic-order index-shaped endpoint-membership predicate — true iff the usize argument equals 0 (the lex-order head-endpoint’s slot in Self::sorted_variants, where the argument is interpreted as a LEX position — the natural output shape of Self::sorted_index_of, Self::sorted_next_index, Self::sorted_prev_index, Self::cycle_sorted_next_index, and Self::cycle_sorted_prev_index) OR T::CARDINALITY - 1 (the lex-order tail-endpoint’s slot), false on every strictly-lex- interior lex slot AND on every out-of-range usize. Closes the (usize, lex, endpoint) corner of the (arg-type × ordering × predicate-flavor) 3×2×2 = 12-corner boolean-boundary hypercube alongside Self::is_endpoint_index (usize, declaration, endpoint).

fn is_sorted_interior_index(i: usize) -> bool

The lexicographic-order index-shaped interior-membership predicate — true iff i names the lex slot of a strictly- lex-interior variant, false on both lex-endpoint slots AND on every out-of-range usize. Closes the (usize, lex, interior) corner AND the FINAL corner of the (arg-type × ordering × predicate-flavor) 3×2×2 = 12-corner boolean-boundary hypercube alongside Self::is_sorted_endpoint_index (usize, lex, endpoint), Self::is_endpoint_index (usize, declaration, endpoint), Self::is_interior_index (usize, declaration, interior), and the pre-existing eight Self-and-&str corners.

fn endpoints() -> (Self, Self)

The declaration-order endpoint anchor pair — the tuple (T::first(), T::last()) projected onto the trait surface as ONE call. Closes the pair-aggregation corner of the closed-set endpoint-anchor return-shape axis on the DECLARATION side — the missing middle column between the two scalar endpoint primitives (Self::first, Self::last) and the collection aggregation ([Self::variants]).

fn sorted_endpoints() -> (Self, Self)

The lexicographic-order endpoint anchor pair — the tuple (T::sorted_first(), T::sorted_last()) projected onto the trait surface as ONE call. Closes the pair-aggregation corner of the closed-set endpoint-anchor return-shape axis on the LEX side.

fn endpoint_labels() -> (&'static str, &'static str)

The declaration-order endpoint-label pair — the tuple (T::first().label(), T::last().label()) projected onto the trait surface as ONE call. Closes the (&'static str, &'static str) pair-aggregation corner of the closed-set endpoint return-shape axis on the declaration side.

fn sorted_endpoint_labels() -> (&'static str, &'static str)

The lexicographic-order endpoint-label pair — the tuple (T::sorted_first().label(), T::sorted_last().label()) projected onto the trait surface as ONE call. Closes the (&'static str, &'static str) pair-aggregation corner of the closed-set endpoint return-shape axis on the LEX side.

fn endpoint_indices() -> (usize, usize)

The declaration-order endpoint DECL-INDEX pair — the tuple (T::first().index_of(), T::last().index_of()) projected onto the trait surface as ONE call. Opens the (usize, usize) pair- aggregation row on the closed-set endpoint-anchor pair return-shape matrix at the (declaration) ordering corner, mirroring Self::endpoint_labels one return-type axis over on the ((&'static str, &'static str), (usize, usize)) return- shape column of the pair-endpoint aggregation matrix AND mirroring Self::first_index + Self::last_index one aggregation-shape axis over on the (singular scalar, pair-tuple) partition of the closed-set declaration-axis endpoint-decl-slot return-shape column.

fn sorted_endpoint_indices() -> (usize, usize)

The lexicographic-order endpoint DECL-INDEX pair — the tuple (T::sorted_first().index_of(), T::sorted_last().index_of()) projected onto the trait surface as ONE call. Closes the (return-type × ordering) 3×2 = 6-corner pair-endpoint aggregation matrix at the (usize, lex) corner alongside the other five corners: Self::endpoints + Self::sorted_endpoints on the (Self, Self) row, Self::endpoint_labels + Self::sorted_endpoint_labels on the (&'static str, &'static str) row, and Self::endpoint_indices (this method’s declaration-axis sibling) on the (usize, usize) row.

fn endpoint_labels_joined(sep: &str) -> String

Render the declaration-order endpoint-label pair as a String joined by sep — the joined-String sibling of Self::endpoint_labels one return-shape axis over on the (tuple, String) partition of the closed-set declaration-axis endpoint-label return-shape axis.

fn sorted_endpoint_labels_joined(sep: &str) -> String

Render the lex-order endpoint-label pair as a String joined by sep — the alphabetized endpoint-label-as-string sibling of Self::endpoint_labels_joined one ordering axis over on the (declaration, lex) partition of the closed-set endpoint- label-as-string surface.

fn interior() -> Vec<Self>

The declaration-order strict-interior variant list — the Vec<Self> complement of Self::endpoints over the closed- set boundary-partition axis. Every variant v in the returned vector satisfies <Self as ClosedSet>::is_interior(v) == true (v is neither Self::first nor Self::last); the declaration order of Self::ALL is preserved verbatim.

fn sorted_interior() -> Vec<Self>

The lexicographic-order strict-interior variant list — the Vec<Self> complement of Self::sorted_endpoints over the closed-set lex-boundary-partition axis. Every variant v in the returned vector satisfies <Self as ClosedSet>::is_sorted_interior(v) == true (v is neither Self::sorted_first nor Self::sorted_last); the lex order of Self::sorted_variants is preserved verbatim.

fn interior_labels() -> Vec<&'static str>

The declaration-order strict-interior label list — the Vec<&'static str> label projection of Self::interior over the closed-set declaration-axis boundary-partition surface. Every label s in the returned vector is the canonical Self::label rendering of some strictly-interior variant (<Self as ClosedSet>::is_interior(v) == true for the sourcing variant, so s is neither Self::first’s label nor Self::last’s label); the declaration order of Self::interior is preserved verbatim.

fn sorted_interior_labels() -> Vec<&'static str>

The lexicographic-order strict-interior label list — the Vec<&'static str> label projection of Self::sorted_interior over the closed-set lex-axis boundary-partition surface. Every label s in the returned vector is the canonical Self::label rendering of some strictly-lex-interior variant (<Self as ClosedSet>::is_sorted_interior(v) == true for the sourcing variant, so s is neither Self::sorted_first’s label nor Self::sorted_last’s label); the lex order of Self::sorted_interior is preserved verbatim.

fn interior_labels_joined(sep: &str) -> String

Render the declaration-order strict-interior label collection as a String joined by sep — the substrate-wide alphabetized- vs-declaration interior-label-as-string surface consumers thread into structured diagnostics that want the boundary-stripped candidate list in a caller-supplied separator style (interior: beta, gamma, delta, middle-only: beta/gamma, an interior-only expected one of the middle kinds: … metrics tag whose surface must NOT leak the two endpoint anchors).

fn sorted_interior_labels_joined(sep: &str) -> String

Render the lex-order strict-interior label collection as a String joined by sep — the alphabetized interior-label-as- string sibling of Self::interior_labels_joined one ordering axis over on the (declaration, lex) partition of the closed-set interior-label-as-string surface.

fn interior_indices() -> Vec<usize>

The declaration-order strict-interior index list — the Vec<usize> decl-slot projection of Self::interior over the closed-set declaration-axis boundary-partition surface. Every index i in the returned vector is the Self::index_of declaration-slot of some strictly-interior variant v in Self::interior (<Self as ClosedSet>::is_interior(v) == true, equivalently <Self as ClosedSet>::is_interior_index(i) == true), so i names neither 0 (the decl-head endpoint slot) nor Self::CARDINALITY - 1 (the decl-tail endpoint slot); the declaration order of Self::interior is preserved verbatim.

fn sorted_interior_indices() -> Vec<usize>

The lex-order strict-interior index list — the Vec<usize> decl-slot projection of Self::sorted_interior over the closed-set lex-axis boundary-partition surface. Every index i in the returned vector is the Self::index_of declaration-slot of some strictly-lex-interior variant v in Self::sorted_interior (<Self as ClosedSet>::is_sorted_interior(v) == true, equivalently <Self as ClosedSet>::is_sorted_interior_index(<Self as ClosedSet>::sorted_index_of(v)) == true), so i names neither the decl slot of Self::sorted_first nor the decl slot of Self::sorted_last; the lex order of Self::sorted_interior is preserved verbatim (the returned vector’s entries are ORDERED by lex position but each entry carries the DECLARATION slot the variant sits at in Self::ALL, not the lex slot — the same usize carrier Self::interior_indices returns one ordering axis over).

fn label_at(i: usize) -> Option<&'static str>

Recover the canonical Self::label at declaration-order position i in Self::ALL, or None if i >= Self::CARDINALITY.

fn index_of_label(s: &str) -> Option<usize>

Recover the declaration-order usize position in Self::ALL of the variant labelled s, or None if s matches no variant’s Self::label.

fn parse_index_of_label(s: &str) -> Result<usize, Self::Unknown>

Allocating-carrier structured decode of s into a declaration- order Self::ALL index — Ok(idx) when s matches some v.label() exactly (where idx == v.index_of()), and Err(Self::make_unknown(s)) for every other string.

fn index_of_label_with_hint(s: &str) -> Result<usize, Option<Self>>

The (hint) sibling of Self::index_of_label — the zero- allocation structured decode of s into a declaration-order index, threading a typed Self::suggest_closest hint into the rejection envelope. Peer of Self::find_by_label_with_hint on the (usize-typed direct projection) axis of the closed-set structured-decode surface: where Self::find_by_label_with_hint returns the typed variant on match, this method projects that variant through Self::index_of so the caller gets the declaration-order slot directly.

fn parse_index_of_label_with_hint( s: &str, ) -> Result<usize, (Self::Unknown, Option<Self>)>

Allocating-carrier structured decode of s into a declaration- order Self::ALL index THREADING a typed Self::suggest_closest hint alongside the substrate-wide Self::Unknown carrier on the reject arm — the (hint) sibling of Self::parse_index_of_label one hint-axis over on the (allocating carrier, &str → usize decl-order decode) surface AND the (usize-typed direct projection) sibling of Self::parse_label_with_hint one return-type-axis over on the (allocating carrier, with-hint) surface. Where Self::parse_index_of_label returns Result<usize, Self::Unknown> (no hint threading), this method widens the reject arm to (Self::Unknown, Option<Self>) so a downstream ?-operator-chained decoder gets BOTH the substrate- wide unknown {SET_LABEL}: {input} carrier AND the typed Self::suggest_closest near-miss slot through ONE call.

fn sorted_index_of(self) -> usize

The declaration-order-index sibling of Self::index_of one ordering-axis over — the direct (typed variant → usize lexicographic-order index) projection through the closed set, keyed on Self::label under the standard-library str: Ord ordering. Returns the position v would occupy in Self::sorted_variants — equivalently, the count of canonical labels strictly less than Self::label(self) under str::cmp.

fn from_sorted_index(i: usize) -> Option<Self>

Recover the typed variant at lexicographic-order position i in Self::sorted_variants, or None if i >= Self::CARDINALITY.

fn sorted_label_at(i: usize) -> Option<&'static str>

Recover the canonical Self::label at lexicographic-order position i in Self::sorted_labels, or None if i >= Self::CARDINALITY.

fn sorted_index_of_label(s: &str) -> Option<usize>

Recover the lexicographic-order usize position of the variant labelled s, or None if s matches no variant’s Self::label.

fn sorted_index_of_label_with_hint(s: &str) -> Result<usize, Option<Self>>

The (hint) sibling of Self::sorted_index_of_label — the zero- allocation structured decode of s into a lexicographic-order index, threading a typed Self::suggest_closest hint into the rejection envelope. Peer of Self::index_of_label_with_hint one ordering-axis over on the (usize-typed direct projection with hint) surface: where Self::index_of_label_with_hint projects the accept-arm variant through Self::index_of (declaration order), this method projects it through Self::sorted_index_of (lex order), so the caller gets the canonical alphabetic-order slot directly.

fn parse_sorted_index_of_label(s: &str) -> Result<usize, Self::Unknown>

Allocating-carrier structured decode of s into a lexicographic-order index, threading the substrate-wide unknown {SET_LABEL}: {input} Self::Unknown carrier through the reject arm — the ordering-axis sibling of Self::parse_index_of_label one ordering-axis over on the (allocating-carrier &str → usize decode, no-hint) surface. Where Self::parse_index_of_label projects the accept-arm variant through Self::index_of (declaration order), this method projects it through Self::sorted_index_of (lex order), so the caller gets the canonical alphabetic-order slot directly through ONE call the substrate’s diagnostic engine binds to.

fn parse_sorted_index_of_label_with_hint( s: &str, ) -> Result<usize, (Self::Unknown, Option<Self>)>

Allocating-carrier structured decode of s into a lexicographic-order Self::ALL index THREADING a typed Self::suggest_closest hint alongside the substrate-wide Self::Unknown carrier on the reject arm — the (ordering) sibling of Self::parse_index_of_label_with_hint one ordering-axis over on the (allocating carrier, &str → usize with-hint) surface AND the (side-effect) sibling of Self::sorted_index_of_label_with_hint one side-effect axis over on the (&str → usize lex-order with-hint) surface AND the (hint) sibling of Self::parse_sorted_index_of_label one hint-axis over on the (allocating carrier, &str → usize lex-order) surface. Where Self::parse_index_of_label_with_hint projects the accept-arm variant through Self::index_of (declaration order), this method projects it through Self::sorted_index_of (lex order), so the caller gets the canonical alphabetic-order slot AND the substrate-wide Self::Unknown carrier AND the typed Self::suggest_closest near-miss slot through ONE call the substrate’s diagnostic engine binds to.

fn next(self) -> Option<Self>

The declaration-order neighbor immediately AFTER self in Self::ALL — Some(Self::ALL[self.index_of() + 1]) when self is not the tail, None otherwise.

fn prev(self) -> Option<Self>

The declaration-order neighbor immediately BEFORE self in Self::ALL — Some(Self::ALL[self.index_of() - 1]) when self is not the head, None otherwise.

fn next_label(self) -> Option<&'static str>

The canonical &'static str LABEL of the declaration-order neighbor immediately AFTER self in Self::ALL — the label of Self::next projected through Self::label, or None when self is the declaration-order tail-endpoint.

fn prev_label(self) -> Option<&'static str>

The canonical &'static str LABEL of the declaration-order neighbor immediately BEFORE self in Self::ALL — the label of Self::prev projected through Self::label, or None when self is the declaration-order head-endpoint.

fn next_index(self) -> Option<usize>

The usize DECLARATION-ORDER INDEX of the neighbor immediately AFTER self in Self::ALL — the position of Self::next projected through Self::index_of, or None when self is the declaration-order tail-endpoint.

fn prev_index(self) -> Option<usize>

The usize DECLARATION-ORDER INDEX of the neighbor immediately BEFORE self in Self::ALL — the position of Self::prev projected through Self::index_of, or None when self is the declaration-order head-endpoint.

fn sorted_next_index(self) -> Option<usize>

The usize LEXICOGRAPHIC-ORDER INDEX of the neighbor immediately AFTER self in Self::sorted_variants — the lex position of Self::sorted_next projected through Self::sorted_index_of, or None when self is the lex-tail-endpoint.

fn sorted_prev_index(self) -> Option<usize>

The usize LEXICOGRAPHIC-ORDER INDEX of the neighbor immediately BEFORE self in Self::sorted_variants — the lex position of Self::sorted_prev projected through Self::sorted_index_of, or None when self is the lex- head-endpoint.

fn sorted_next_label(self) -> Option<&'static str>

The canonical &'static str LABEL of the lexicographic-order neighbor immediately AFTER self in Self::sorted_variants — the label of Self::sorted_next projected through Self::label, or None when self is the lex-tail-endpoint.

fn sorted_prev_label(self) -> Option<&'static str>

The canonical &'static str LABEL of the lexicographic-order neighbor immediately BEFORE self in Self::sorted_variants — the label of Self::sorted_prev projected through Self::label, or None when self is the lex-head-endpoint.

fn sorted_next(self) -> Option<Self>

The lexicographic-order neighbor immediately AFTER self in Self::sorted_variants — Some(Self::sorted_variants()[ self.sorted_index_of() + 1]) when self is not the lex-tail, None otherwise.

fn sorted_prev(self) -> Option<Self>

The lexicographic-order neighbor immediately BEFORE self in Self::sorted_variants — Some(Self::sorted_variants()[ self.sorted_index_of() - 1]) when self is not the lex-head, None otherwise.

fn cycle_next(self) -> Self

The declaration-order neighbor immediately AFTER self in Self::ALL, WRAPPING to Self::first at the tail — self.next().unwrap_or(Self::first()). Returns Self, never Option<Self>: the wrapping arm folds the tail- endpoint boundary onto the head-endpoint anchor rather than leaving the None the bounded-neighbor axis returns.

fn cycle_prev(self) -> Self

The declaration-order neighbor immediately BEFORE self in Self::ALL, WRAPPING to Self::last at the head — self.prev().unwrap_or(Self::last()). Returns Self, never Option<Self>: the wrapping arm folds the head-endpoint boundary onto the tail-endpoint anchor rather than leaving the None the bounded-neighbor axis returns.

fn cycle_sorted_next(self) -> Self

The lexicographic-order neighbor immediately AFTER self in Self::sorted_variants, WRAPPING to Self::sorted_first at the lex tail — self.sorted_next().unwrap_or(Self::sorted_first()). Returns Self, never Option<Self>: the wrapping arm folds the lex-tail-endpoint boundary onto the lex-head-endpoint anchor rather than leaving the None the bounded-lex-neighbor axis returns.

fn cycle_sorted_prev(self) -> Self

The lexicographic-order neighbor immediately BEFORE self in Self::sorted_variants, WRAPPING to Self::sorted_last at the lex head — self.sorted_prev().unwrap_or(Self::sorted_last()). Returns Self, never Option<Self>: the wrapping arm folds the lex-head-endpoint boundary onto the lex-tail-endpoint anchor rather than leaving the None the bounded-lex-neighbor axis returns.

fn cycle_next_label(self) -> &'static str

The canonical &'static str LABEL of the declaration-order neighbor immediately AFTER self in Self::ALL, WRAPPING to Self::first_label at the tail — the label of Self::cycle_next projected through Self::label. Returns &'static str, never Option<&'static str>: the wrapping arm folds the tail-endpoint boundary onto the head-endpoint anchor label rather than leaving the None the bounded-neighbor- label axis returns.

fn cycle_prev_label(self) -> &'static str

The canonical &'static str LABEL of the declaration-order neighbor immediately BEFORE self in Self::ALL, WRAPPING to Self::last_label at the head — the label of Self::cycle_prev projected through Self::label. Returns &'static str, never Option<&'static str>.

fn cycle_sorted_next_label(self) -> &'static str

The canonical &'static str LABEL of the lexicographic-order neighbor immediately AFTER self in Self::sorted_variants, WRAPPING to Self::sorted_first_label at the lex tail — the label of Self::cycle_sorted_next projected through Self::label. Returns &'static str, never Option<&'static str>.

fn cycle_sorted_prev_label(self) -> &'static str

The canonical &'static str LABEL of the lexicographic-order neighbor immediately BEFORE self in Self::sorted_variants, WRAPPING to Self::sorted_last_label at the lex head — the label of Self::cycle_sorted_prev projected through Self::label. Returns &'static str, never Option<&'static str>.

fn cycle_next_index(self) -> usize

The usize DECLARATION-ORDER INDEX of the neighbor immediately AFTER self in Self::ALL, WRAPPING to 0 at the tail — the declaration-order position of Self::cycle_next projected through Self::index_of. Returns usize, never Option<usize>: the wrapping arm folds the tail-endpoint boundary onto the head-index-anchor 0 rather than leaving the None the bounded-neighbor-index axis returns.

fn cycle_prev_index(self) -> usize

The usize DECLARATION-ORDER INDEX of the neighbor immediately BEFORE self in Self::ALL, WRAPPING to T::CARDINALITY - 1 at the head — the declaration-order position of Self::cycle_prev projected through Self::index_of. Returns usize, never Option<usize>: the wrapping arm folds the head-endpoint boundary onto the tail-index-anchor rather than leaving the None the bounded-neighbor-index axis returns.

fn cycle_sorted_next_index(self) -> usize

The usize LEXICOGRAPHIC-ORDER INDEX of the neighbor immediately AFTER self in Self::sorted_variants, WRAPPING to 0 at the lex tail — the lex position of Self::cycle_sorted_next projected through Self::sorted_index_of. Returns usize, never Option<usize>: the wrapping arm folds the lex-tail- endpoint boundary onto the lex-head-index-anchor 0 rather than leaving the None the bounded-lex-neighbor-index axis returns.

fn cycle_sorted_prev_index(self) -> usize

The usize LEXICOGRAPHIC-ORDER INDEX of the neighbor immediately BEFORE self in Self::sorted_variants, WRAPPING to T::CARDINALITY - 1 at the lex head — the lex position of Self::cycle_sorted_prev projected through Self::sorted_index_of. Returns usize, never Option<usize>: the wrapping arm folds the lex-head-endpoint boundary onto the lex-tail-index-anchor rather than leaving the None the bounded-lex-neighbor-index axis returns.

fn precedes(self, other: Self) -> bool

The declaration-order strict-precedence pairwise predicate — true iff self appears strictly before other in Self::ALL’s declaration order, false on equality or when self appears strictly after other. The binary peer of every pre-existing UNARY declaration-axis endpoint predicate (Self::is_first, Self::is_last, Self::is_endpoint, Self::is_interior, Self::is_first_label, Self::is_last_label, Self::is_endpoint_label, Self::is_interior_label, Self::is_first_index, Self::is_last_index, Self::is_endpoint_index, Self::is_interior_index) — those methods answer “where does this ONE variant sit in the declaration axis,” this method answers “which of these TWO variants sits earlier in the declaration axis.” Opens the (self, other) pairwise-comparison axis on the closed-set surface at the declaration-order strict-less-than corner.

fn succeeds(self, other: Self) -> bool

The declaration-order strict-succession pairwise predicate — true iff self appears strictly AFTER other in Self::ALL’s declaration order, false on equality or when self appears strictly before other. The direction-complement arm of Self::precedes on the (forward, backward) axis of the declaration-order pairwise-comparison surface.

fn sorted_precedes(self, other: Self) -> bool

The lex-order strict-precedence pairwise predicate — true iff self appears strictly before other in lexicographic order over Self::label’s projection, false on equality or when self appears strictly after other. The lex-ordering peer of Self::precedes on the (declaration, lex) ordering axis of the pairwise-comparison surface.

fn sorted_succeeds(self, other: Self) -> bool

The lex-order strict-succession pairwise predicate — true iff self appears strictly AFTER other in lexicographic order over Self::label’s projection, false on equality or when self appears strictly before other. The direction-complement of Self::sorted_precedes on the (forward, backward) direction axis of the lex-ordering pairwise-comparison surface.

fn precedes_or_equal(self, other: Self) -> bool

The declaration-order non-strict-precedence pairwise predicate — true iff self appears before OR is equal to other in Self::ALL’s declaration order, false when self appears strictly after other. The strictness-complement of Self::precedes on the (strict, non-strict) axis of the declaration-order pairwise-comparison surface.

fn succeeds_or_equal(self, other: Self) -> bool

The declaration-order non-strict-succession pairwise predicate — true iff self appears AFTER OR is equal to other in Self::ALL’s declaration order, false when self appears strictly before other. The direction-complement arm of Self::precedes_or_equal on the (forward, backward) axis of the declaration-order non-strict pairwise-comparison surface.

fn sorted_precedes_or_equal(self, other: Self) -> bool

The lex-order non-strict-precedence pairwise predicate — true iff self appears before OR is equal to other in lexicographic order over Self::label’s projection, false when self appears strictly after other. The lex-ordering peer of Self::precedes_or_equal on the (declaration, lex) ordering axis of the non-strict pairwise-comparison surface.

fn sorted_succeeds_or_equal(self, other: Self) -> bool

The lex-order non-strict-succession pairwise predicate — true iff self appears AFTER OR is equal to other in lexicographic order over Self::label’s projection, false when self appears strictly before other. The direction-complement of Self::sorted_precedes_or_equal on the (forward, backward) direction axis of the lex-ordering non-strict pairwise- comparison surface.

fn min(self, other: Self) -> Self

The declaration-order binary pairwise MIN projection — the earlier of self and other in Self::ALL’s declaration order. Returns self when self.precedes_or_equal(other) (so ties fold to self, matching Rust’s core::cmp::min tie- break convention), returns other otherwise.

fn max(self, other: Self) -> Self

The declaration-order binary pairwise MAX projection — the later of self and other in Self::ALL’s declaration order. Returns self when self.succeeds_or_equal(other) (ties fold to self, mirroring Self::min’s tie-break- left convention across the (min, max) axis), returns other otherwise. The direction-complement arm of Self::min on the (min, max) axis of the declaration-order binary pairwise-selection surface.

fn sorted_min(self, other: Self) -> Self

The lex-order binary pairwise MIN projection — the lex- earlier of self and other under Self::label’s projection into ASCII lexicographic order. Returns self when self.sorted_precedes_or_equal(other) (ties fold to self), returns other otherwise. The lex-ordering peer of Self::min on the (declaration, lex) ordering axis of the binary pairwise-selection surface.

fn sorted_max(self, other: Self) -> Self

The lex-order binary pairwise MAX projection — the lex- later of self and other under Self::label’s projection into ASCII lexicographic order. Returns self when self.sorted_succeeds_or_equal(other) (ties fold to self), returns other otherwise. Closes the (ordering × direction) 2×2 = 4-corner binary pairwise-selection matrix on the closed-set surface at the (lex-order, max) corner — sibling posture to Self::sorted_min one direction axis over on the lex arm AND to Self::max one ordering axis over on the max arm.

fn min_label(self, other: Self) -> &'static str

The canonical &'static str LABEL of the declaration-order binary pairwise-MIN projection of self and other — the label of Self::min projected through Self::label. Returns &'static str, never Option<&'static str>: the binary min projection is TOTAL on every operand pair, and every variant carries a canonical label.

fn max_label(self, other: Self) -> &'static str

The canonical &'static str LABEL of the declaration-order binary pairwise-MAX projection of self and other — the label of Self::max projected through Self::label. Returns &'static str, never Option<&'static str>.

fn sorted_min_label(self, other: Self) -> &'static str

The canonical &'static str LABEL of the lex-order binary pairwise-MIN projection of self and other — the label of Self::sorted_min projected through Self::label. Returns &'static str, never Option<&'static str>.

fn sorted_max_label(self, other: Self) -> &'static str

The canonical &'static str LABEL of the lex-order binary pairwise-MAX projection of self and other — the label of Self::sorted_max projected through Self::label. Returns &'static str, never Option<&'static str>.

fn min_index(self, other: Self) -> usize

The usize DECLARATION-ORDER INDEX of the declaration-order binary pairwise-MIN projection of self and other — the declaration-order position of Self::min projected through Self::index_of. Returns usize, never Option<usize>: the binary min projection is TOTAL on every operand pair, and every variant carries a declaration-order slot.

fn max_index(self, other: Self) -> usize

The usize DECLARATION-ORDER INDEX of the declaration-order binary pairwise-MAX projection of self and other — the declaration-order position of Self::max projected through Self::index_of. Returns usize, never Option<usize>.

fn sorted_min_index(self, other: Self) -> usize

The usize LEXICOGRAPHIC-ORDER INDEX of the lex-order binary pairwise-MIN projection of self and other — the lex position of Self::sorted_min projected through Self::sorted_index_of. Returns usize, never Option<usize>.

fn sorted_max_index(self, other: Self) -> usize

The usize LEXICOGRAPHIC-ORDER INDEX of the lex-order binary pairwise-MAX projection of self and other — the lex position of Self::sorted_max projected through Self::sorted_index_of. Returns usize, never Option<usize>.

fn min_of(items: &[Self]) -> Option<Self>

The declaration-order N-ARY MIN projection — the earliest variant of items under Self::ALL’s declaration order, or None when items is empty. Folds Self::min over items from left via Iterator::reduce: the singleton case returns Some(items[0]), the k-length case returns Some(items.iter().copied().reduce(min).unwrap()). The arity-N opener on the closed-set surface past the exhaustively- closed 12-corner binary pairwise-SELECTION hypercube (95)+(96)+ (97)+(98)+(99)+(100) — opens the arity axis one step further from binary pairwise-selection to N-ary variadic reduction over a slice.

fn max_of(items: &[Self]) -> Option<Self>

The declaration-order N-ARY MAX projection — the latest variant of items under Self::ALL’s declaration order, or None when items is empty. Folds Self::max over items from left via Iterator::reduce.

fn sorted_min_of(items: &[Self]) -> Option<Self>

The lex-order N-ARY MIN projection — the lex-earliest variant of items under Self::label’s projection into ASCII lexicographic order, or None when items is empty. Folds Self::sorted_min over items from left via Iterator::reduce.

fn sorted_max_of(items: &[Self]) -> Option<Self>

The lex-order N-ARY MAX projection — the lex-latest variant of items under Self::label’s projection into ASCII lexicographic order, or None when items is empty. Folds Self::sorted_max over items from left via Iterator::reduce.

fn min_label_of(items: &[Self]) -> Option<&'static str>

The canonical &'static str LABEL of the declaration-order N-ARY MIN projection of items — the label of Self::min_of projected through Self::label, or None when items is empty. The label-return-shape peer of Self::min_of one return-shape axis over on the N-ary variadic-reduction surface, AND the N-ary-arity peer of Self::min_label one arity level up. Opens the label-return column of the (return-shape × ordering × direction) 3×2×2 = 12-corner N-ary variadic-reduction hypercube past the exhaustively-closed 4-corner Self-return face Self::min_of / Self::max_of / Self::sorted_min_of / Self::sorted_max_of — the N-ary counterpart of the binary pairwise-selection hypercube’s own return-shape column Self::min_label / Self::max_label / Self::sorted_min_label / Self::sorted_max_label one arity level down.

fn max_label_of(items: &[Self]) -> Option<&'static str>

The canonical &'static str LABEL of the declaration-order N-ARY MAX projection of items — the label of Self::max_of projected through Self::label, or None when items is empty.

fn sorted_min_label_of(items: &[Self]) -> Option<&'static str>

The canonical &'static str LABEL of the lex-order N-ARY MIN projection of items — the label of Self::sorted_min_of projected through Self::label, or None when items is empty.

fn sorted_max_label_of(items: &[Self]) -> Option<&'static str>

The canonical &'static str LABEL of the lex-order N-ARY MAX projection of items — the label of Self::sorted_max_of projected through Self::label, or None when items is empty.

fn min_index_of(items: &[Self]) -> Option<usize>

The usize DECLARATION-ORDER INDEX of the declaration-order N-ARY MIN projection of items — the declaration-order position of Self::min_of projected through Self::index_of, or None when items is empty. The index-return-shape peer of Self::min_of one return-shape axis over on the N-ary variadic-reduction surface, AND the N-ary-arity peer of Self::min_index one arity level up. Opens the index-return column of the (return-shape × ordering × direction) 3×2×2 = 12-corner N-ary variadic-reduction hypercube past the pre- existing Self-return 4-corner face Self::min_of / Self::max_of / Self::sorted_min_of / Self::sorted_max_of AND the label-return 4-corner face Self::min_label_of / Self::max_label_of / Self::sorted_min_label_of / Self::sorted_max_label_of — the N-ary counterpart of the binary pairwise-selection hypercube’s own index-return column Self::min_index / Self::max_index / Self::sorted_min_index / Self::sorted_max_index one arity level down.

fn max_index_of(items: &[Self]) -> Option<usize>

The usize DECLARATION-ORDER INDEX of the declaration-order N-ARY MAX projection of items — the declaration-order position of Self::max_of projected through Self::index_of, or None when items is empty.

fn sorted_min_index_of(items: &[Self]) -> Option<usize>

The usize LEXICOGRAPHIC-ORDER INDEX of the lex-order N-ARY MIN projection of items — the lex position of Self::sorted_min_of projected through Self::sorted_index_of, or None when items is empty.

fn sorted_max_index_of(items: &[Self]) -> Option<usize>

The usize LEXICOGRAPHIC-ORDER INDEX of the lex-order N-ARY MAX projection of items — the lex position of Self::sorted_max_of projected through Self::sorted_index_of, or None when items is empty.

fn is_ascending(items: &[Self]) -> bool

The declaration-order N-ARY NON-STRICT ASCENDING monotonicity predicate — true iff every consecutive pair (items[i], items[i+1]) satisfies items[i].precedes_or_equal(items[i+1]) under Self::ALL’s declaration order, false on the first consecutive pair that violates non-strict precedence. Folds Self::precedes_or_equal over items.windows(2) via Iterator::all — vacuously true on the empty slice AND on every singleton slice (no adjacent pairs), threading the (0 && 1)-length identity of Iterator::all on windows(2) through bool’s conjunctive fold.

fn is_descending(items: &[Self]) -> bool

The declaration-order N-ARY NON-STRICT DESCENDING monotonicity predicate — true iff every consecutive pair (items[i], items[i+1]) satisfies items[i].succeeds_or_equal(items[i+1]) under Self::ALL’s declaration order, false on the first consecutive pair that violates non-strict succession. The direction-complement arm of Self::is_ascending on the (forward, backward) axis of the N-ary monotonicity surface.

fn is_sorted_ascending(items: &[Self]) -> bool

The lex-order N-ARY NON-STRICT ASCENDING monotonicity predicate — true iff every consecutive pair (items[i], items[i+1]) satisfies items[i].sorted_precedes_or_equal(items[i+1]) under Self::label’s projection into ASCII lexicographic order, false on the first consecutive pair that violates non-strict lex-precedence. The lex-ordering peer of Self::is_ascending on the (declaration, lex) ordering axis of the N-ary monotonicity surface.

fn is_sorted_descending(items: &[Self]) -> bool

The lex-order N-ARY NON-STRICT DESCENDING monotonicity predicate — true iff every consecutive pair (items[i], items[i+1]) satisfies items[i].sorted_succeeds_or_equal(items[i+1]) under Self::label’s projection into ASCII lexicographic order, false on the first consecutive pair that violates non-strict lex-succession. Closes the (ordering × direction) 2×2 = 4-corner N-ary non-strict monotonicity matrix on the closed-set surface at the (lex-order, descending) corner past the three prior corners at (declaration, ascending) / (declaration, descending) / (lex, ascending).

fn is_strictly_ascending(items: &[Self]) -> bool

The declaration-order N-ARY STRICT ASCENDING monotonicity predicate — true iff every consecutive pair (items[i], items[i+1]) satisfies items[i].precedes(items[i+1]) under Self::ALL’s declaration order, false on the first consecutive pair that violates strict precedence (including any adjacent equal pair, by irreflexivity of the strict pairwise-precedence primitive). The strictness-complement arm of Self::is_ascending on the (strict, non-strict) axis of the N-ary monotonicity surface.

fn is_strictly_descending(items: &[Self]) -> bool

The declaration-order N-ARY STRICT DESCENDING monotonicity predicate — true iff every consecutive pair (items[i], items[i+1]) satisfies items[i].succeeds(items[i+1]) under Self::ALL’s declaration order, false on the first consecutive pair that violates strict succession (including any adjacent equal pair). The direction-complement arm of Self::is_strictly_ascending on the (forward, backward) axis of the N-ary strict-monotonicity surface AND the strictness-complement arm of Self::is_descending on the (strict, non-strict) axis.

fn is_sorted_strictly_ascending(items: &[Self]) -> bool

The lex-order N-ARY STRICT ASCENDING monotonicity predicate — true iff every consecutive pair (items[i], items[i+1]) satisfies items[i].sorted_precedes(items[i+1]) under Self::label’s projection into ASCII lexicographic order, false on the first consecutive pair that violates strict lex-precedence. The lex-ordering peer of Self::is_strictly_ascending on the (declaration, lex) ordering axis of the N-ary strict-monotonicity surface AND the strictness-complement arm of Self::is_sorted_ascending on the (strict, non-strict) axis.

fn is_sorted_strictly_descending(items: &[Self]) -> bool

The lex-order N-ARY STRICT DESCENDING monotonicity predicate — true iff every consecutive pair (items[i], items[i+1]) satisfies items[i].sorted_succeeds(items[i+1]) under Self::label’s projection into ASCII lexicographic order, false on the first consecutive pair that violates strict lex-succession. Closes the (ordering × direction × strictness) 2×2×2 = 8-corner N-ary monotonicity hypercube on the closed- set surface at the (lex-order, descending, strict) corner past the seven prior corners at the four non-strict corners (105)+(106)+(107)+(108) and the three prior strict corners (declaration, ascending, strict), (declaration, descending, strict), (lex, ascending, strict).

fn is_monotonic(items: &[Self]) -> bool

The declaration-order N-ARY NON-STRICT DIRECTION-COLLAPSED monotonicity predicate — true iff items is EITHER non- strictly ascending OR non-strictly descending under Self::ALL’s declaration order, false when items fails BOTH directions. The DIRECTION-COLLAPSED opener on the N-ary monotonicity surface past the exhaustively-closed 8-corner (arity-N × ordering × direction × strictness) 2×2×2 monotonicity hypercube (105)+(106)+(107)+(108)+(109)+(110)+(111)+(112) — opens the (direction-collapsed) axis one dimension over from the direction-split predicates at the (declaration, non-strict) corner.

fn is_strictly_monotonic(items: &[Self]) -> bool

The declaration-order N-ARY STRICT DIRECTION-COLLAPSED monotonicity predicate — true iff items is EITHER strictly ascending OR strictly descending under Self::ALL’s declaration order, false when items fails BOTH directions (including any slice with two or more adjacent equal elements, by irreflexivity of the strict pairwise-precedence primitive on both direction arms). The strictness-complement arm of Self::is_monotonic on the (strict, non-strict) axis of the direction-collapsed N-ary monotonicity surface.

fn is_sorted_monotonic(items: &[Self]) -> bool

The lex-order N-ARY NON-STRICT DIRECTION-COLLAPSED monotonicity predicate — true iff items is EITHER non-strictly lex- ascending OR non-strictly lex-descending under Self::label’s projection into ASCII lexicographic order, false when items fails BOTH directions. The lex-ordering peer of Self::is_monotonic on the (declaration, lex) ordering axis of the direction-collapsed N-ary monotonicity surface.

fn is_sorted_strictly_monotonic(items: &[Self]) -> bool

The lex-order N-ARY STRICT DIRECTION-COLLAPSED monotonicity predicate — true iff items is EITHER strictly lex-ascending OR strictly lex-descending under Self::label’s projection into ASCII lexicographic order, false when items fails BOTH directions. Closes the (ordering × strictness) 2×2 = 4-corner direction-collapsed N-ary monotonicity matrix on the closed-set surface at the (lex-order, strict) corner past the three prior corners at (declaration, non-strict) / (declaration, strict) / (lex, non-strict).

fn is_constant(items: &[Self]) -> bool

The N-ARY DIRECTION-JOINED “constant slice” predicate — true iff items is BOTH non-strictly ascending AND non-strictly descending under Self::ALL’s declaration order, false otherwise. Since the substrate’s declaration order is total, the joint condition holds iff every adjacent pair is EQUAL, i.e. items is a repetition of ONE variant (possibly zero-arity). The direction- CONJUNCTION peer of Self::is_monotonic’s direction-DISJUNCTION on the (∧, ∨) axis of the N-ary monotonicity face — while Self::is_monotonic widens the direction-split arms through || to accept EITHER ordering, this predicate NARROWS them through && to accept ONLY the constant intersection.

fn is_pairwise_distinct(items: &[Self]) -> bool

The N-ARY ORDERING-AGNOSTIC “pairwise distinct” predicate — true iff every ordered pair of positions (i, j) with i < j in items satisfies items[i] != items[j] (compared via Self::index_of’s total-ordering discriminator), false on the first pair of positions whose variants coincide. The DISTINCTNESS-axis opener on the closed-set surface — dual to Self::is_constant on the (constant, distinct) axis of the N-ary element-equivalence face — while Self::is_constant narrows to slices where every ordered pair AGREES, this predicate widens to slices where every ordered pair DIFFERS.

fn count_distinct(items: &[Self]) -> usize

The N-ARY ORDERING-AGNOSTIC “distinct count” projection — the usize cardinality of the SET of variant identities that occur in items, computed as the count of positions whose variant does not appear at any strictly-lesser position (a “first-occurrence” sweep keyed on Self::index_of). The USIZE-RETURN opener on the (return-shape) column of the N-ary element-equivalence surface past the pre-existing bool-return endpoints Self::is_constant (all elements AGREE) and Self::is_pairwise_distinct (all elements DIFFER) — while both bool-return endpoints answer a YES/NO question about the extremes of the equivalence-partition axis, this projection reports the EXACT distinctness cardinality of the multiset the slice underlies, folding both endpoints into two special values of ONE numerical invariant. Not a fresh substrate primitive on the index axis — the count emerges from the Self::index_of bijection applied position-by-position with a strictly-lesser-position dedup sweep, so the return value is a typed CONSEQUENCE of the substrate’s total-ordering discriminator.

fn is_covering(items: &[Self]) -> bool

The N-ARY ORDERING-AGNOSTIC “covers every variant” surjectivity predicate — true iff every variant of Self::ALL occurs at least once in items. The BOOL-RETURN opener on the (covering) axis of the equivalence-partition surface, positioned as a typed CONSEQUENCE of the just-lifted USIZE-return Self::count_distinct projection reaching the substrate-carried upper bound Self::CARDINALITY. The predicate answers YES/NO to “does this slice HIT every variant?” — dual to Self::is_pairwise_distinct (which answers YES/NO to “does this slice REPEAT any variant?”) on the same equivalence-partition surface, and orthogonal to Self::is_constant (which answers YES/NO to “do all positions SHARE one variant?”). Not a fresh substrate primitive on the index axis — the predicate emerges from a single equality check on the just-lifted usize-return count against the trait-level Self::CARDINALITY constant.

fn is_permutation_of_all(items: &[Self]) -> bool

The BOOL-return N-ARY predicate answering “does this slice visit every variant EXACTLY ONCE?” — the (covering ∧ distinct) CONJUNCTION corner of the equivalence-partition surface, closing the (constant, distinct, covering, permutation) 4- projection square past the three pre-existing typed primitives.

fn count_missing(items: &[Self]) -> usize

The N-ARY ORDERING-AGNOSTIC “missing count” projection — the usize cardinality of the SET of variants of Self::ALL that do NOT occur in items, computed as the substrate-carried Self::CARDINALITY constant minus the just-lifted usize-return Self::count_distinct projection. The USIZE-RETURN opener on the (absent) column of the (present, absent) partition-arm axis of the equivalence-partition surface, positioned as the direct dual of Self::count_distinct one column of the (partition- arm) axis over — while Self::count_distinct reports “how many variants does the slice HIT?”, this projection reports “how many variants does the slice MISS?”, folding the ambient set’s partition into hit and miss cardinalities. Not a fresh substrate primitive on the index axis — the count emerges from one usize-subtraction of the just-lifted usize-return Self::count_distinct projection from the trait-level Self::CARDINALITY constant.

fn is_missing_any(items: &[Self]) -> bool

The N-ARY ORDERING-AGNOSTIC “any variant missing?” predicate — true iff AT LEAST ONE variant of Self::ALL does NOT occur in items, computed as the just-lifted usize-return Self::count_missing projection strictly exceeding zero. The BOOL-RETURN closer on the (absent) arm of the (present, absent) × (bool, usize) 2×2 = 4-corner partition-arm × return-shape face on the equivalence-partition surface, positioned as the direct DE MORGAN dual of Self::is_covering one column of the (partition-arm) axis over — while Self::is_covering reports “does the slice HIT every variant?”, this projection reports “does the slice MISS any variant?”, folding the ambient set’s partition arms through the negation into the bool-return absent-arm. Not a fresh substrate primitive on the index axis — the predicate emerges from one comparison of the just-lifted Self::count_missing projection against zero, equivalently one ! on the just-lifted Self::is_covering predicate.

fn count_occurrences_of(target: Self, items: &[Self]) -> usize

The N-ARY ORDERING-AGNOSTIC PER-TARGET “occurrence count” projection — the usize cardinality of the SET of positions of items whose variant identity coincides with target, computed as a per-position Self::index_of equality-filter through .count(). The PER-TARGET USIZE-RETURN opener on the (per-target × usize) MULTIPLICITY column of the equivalence- partition surface, positioned as the direct PER-TARGET DECOMPOSITION of the just-lifted N-ary set-level Self::count_distinct projection — while Self::count_distinct reports “how many DISTINCT variants does the slice hit?” (a single set-level usize), this projection reports “how many times does THIS variant appear?” (a per-target usize that varies with target). Not a fresh substrate primitive on the index axis — the count emerges from one composition of the substrate’s total-ordering discriminator Self::index_of pinned as a bijection into [0, T::CARDINALITY) by clause (16) with the standard-library filter-through-count combinator.

fn occurs_in(target: Self, items: &[Self]) -> bool

The N-ARY ORDERING-AGNOSTIC PER-TARGET “occurs-in” membership predicate — true iff AT LEAST ONE position of items carries the same variant identity as target, computed as the just- lifted usize-return Self::count_occurrences_of per-target multiplicity projection strictly exceeding zero. The PER-TARGET BOOL-RETURN opener on the (per-target × bool) MEMBERSHIP column of the equivalence-partition surface, positioned as the direct PER-TARGET DECOMPOSITION of the just-lifted N-ary set-level Self::is_covering present-arm predicate one column of the (per-target, set-level) arity axis over — while Self::is_covering reports “does the slice HIT every variant?” (a single set-level bool), this projection reports “does the slice HIT THIS variant?” (a per-target bool that varies with target). The (per-target, set-level) × (bool, usize) 2×2 = 4-corner (arity × return-shape) face on the equivalence-partition surface now closes the bool per-target column at the (bool, per-target) corner peer to the (usize, per-target) corner Self::count_occurrences_of opened.

fn first_occurrence_of(target: Self, items: &[Self]) -> Option<usize>

The N-ARY PER-TARGET “first occurrence position” projection — Some(i) for the SMALLEST slice index i at which items[i] carries the same variant identity as target, or None if target does not appear. The PER-TARGET Option<usize>-RETURN opener on the (per-target × Option<usize>) HEAD-POSITION column of the equivalence-partition surface, positioned as the direct POSITION-VALUE lift of the just-lifted bool-return Self::occurs_in one return-shape axis over — while Self::occurs_in reports “does the slice HIT this variant?” (a per-target bool), this projection reports “at WHICH position does the slice FIRST hit this variant?” (a per-target Option<usize> whose Some arm carries the head-position and whose None arm collapses onto Self::occurs_in’s false arm).

fn last_occurrence_of(target: Self, items: &[Self]) -> Option<usize>

The N-ARY PER-TARGET “last occurrence position” projection — Some(i) for the LARGEST slice index i at which items[i] carries the same variant identity as target, or None if target does not appear. Sibling to Self::first_occurrence_of one endpoint-direction axis over on the (per-target × Option<usize> × endpoint-direction) 2- corner face: Self::first_occurrence_of returns the smallest matching slice index; this method returns the largest.

fn all_occurrences_of(target: Self, items: &[Self]) -> Vec<usize>

The N-ARY PER-TARGET “all occurrence positions” projection — the Vec<usize> of EVERY slice index at which items[i] carries the same variant identity as target, in strictly ascending slice-order. The PER-TARGET Vec<usize>-RETURN opener on the (per-target × Vec<usize>) EVERY-POSITION column of the equivalence-partition surface, positioned as the direct VEC-LIFT of the just-lifted endpoint-anchor pair Self::first_occurrence_of + Self::last_occurrence_of one return-shape axis over — while those two projections report the SMALLEST and LARGEST matching slice indices (a per-target Option<usize> singleton at either endpoint of the matching index set), THIS projection reports the ENTIRE matching index set (a per-target Vec<usize> of every matching slice index). The (per-target × return-shape) row on the equivalence- partition surface now carries five typed corners: Self::count_occurrences_of (usize; multiplicity), Self::occurs_in (bool; membership), Self::first_occurrence_of (Option<usize>; head-position), Self::last_occurrence_of (Option<usize>; tail-position), and THIS projection (Vec<usize>; every-position).

fn occurrence_endpoints_of( target: Self, items: &[Self], ) -> Option<(usize, usize)>

The N-ARY PER-TARGET “occurrence endpoint pair” projection — Some((first, last)) for the SMALLEST + LARGEST slice indices at which items carries the same variant identity as target, or None if target does not appear. The PER-TARGET Option<(usize, usize)>-RETURN opener on the (per-target × Option<(usize, usize)>) ENDPOINT-PAIR column of the equivalence-partition surface, positioned as the direct PAIR- PACKAGED lift of the just-lifted Self::first_occurrence_of + Self::last_occurrence_of endpoint-anchor pair — while the endpoint-anchor pair reports the head- and tail-position across TWO separate Option<usize> returns, this projection packages both endpoints into ONE atomic Option<(usize, usize)> return via Option::zip on the two endpoint-anchor primitives. Sibling posture to Self::variant_count_range one arity axis over: the set-level projection returns (usize, usize) = (min_variant_count, max_variant_count) of the histogram bars; the per-target projection returns Option<(usize, usize)> = the (head-position, tail-position) endpoint pair of a target’s slice occurrences. The (per-target × return-shape) row on the equivalence-partition surface now closes the pair-return column at the (Option<(usize, usize)>, per-target) corner peer to the (Vec<usize>, per-target) corner Self::all_occurrences_of just opened.

fn occurrence_span_of(target: Self, items: &[Self]) -> Option<usize>

The N-ARY ORDERING-AGNOSTIC “per-target endpoint-span” projection — the Option<usize> slot-difference reduction of the Self::occurrence_endpoints_of endpoint-pair corner (Some(l - f) on the Some((f, l)) arm, None when the target does not appear). The PER-TARGET Option<usize>-RETURN SCALAR-DIFFERENCE REDUCTION opener on the (per-target × Option<usize> scalar-difference) column of the equivalence- partition surface, positioned as the direct SCALAR-DIFFERENCE projection of the just-lifted Self::occurrence_endpoints_of pair-return corner. Sibling posture to Self::variant_count_span one arity axis over: the set-level projection returns usize = max_variant_count - min_variant_count = the scalar-difference reduction of the (min-bar, max-bar) direction pair via Self::variant_count_range; the per-target projection returns Option<usize> = l - f = the scalar-difference reduction of the (head, tail) endpoint pair via Self::occurrence_endpoints_of. Both share the same abstract shape “reduce a pair-return corner through slot- subtraction to a scalar” but on different arities of the same substrate — the set-level column reduces the (min-bar, max-bar) direction pair; the per-target column reduces the (head, tail) endpoint pair. The (per-target × return-shape) row on the equivalence-partition surface now closes the Option<usize> scalar-difference column at the (Option<usize>, per-target, scalar-difference) corner peer to the (Option<(usize, usize)>, per-target, pair) corner Self::occurrence_endpoints_of just opened.

fn is_unique_occurrence_of(target: Self, items: &[Self]) -> bool

The N-ARY ORDERING-AGNOSTIC “per-target multiplicity-1” predicate — the bool per-target UNIQUENESS test whose value coincides with T::count_occurrences_of(target, items) == 1, i.e. true iff the target appears EXACTLY ONCE in items. The PER-TARGET bool-RETURN MULTIPLICITY-BAND CLOSER on the (per-target × bool) column of the equivalence-partition surface, positioned as the direct MULTIPLICITY-BAND projection of the just-lifted usize-return Self::count_occurrences_of per- target multiplicity primitive, one MULTIPLICITY-BAND axis over from the (per-target × bool) MULTIPLICITY-POSITIVE corner Self::occurs_in: while Self::occurs_in reports “does the slice HIT this variant at least ONCE?” (multiplicity-band > 0), this projection reports “does the slice HIT this variant EXACTLY ONCE?” (multiplicity-band == 1). The (per- target × bool × multiplicity-band) 2-corner face on the equivalence-partition surface now closes at the (bool, per- target, == 1) corner peer to the (bool, per-target, > 0) corner Self::occurs_in opened.

fn is_repeated_occurrence_of(target: Self, items: &[Self]) -> bool

The N-ARY ORDERING-AGNOSTIC “per-target multiplicity-≥2” predicate — the bool per-target REPETITION test whose value coincides with T::count_occurrences_of(target, items) >= 2, i.e. true iff the target appears AT LEAST TWICE in items. The PER-TARGET bool-RETURN MULTIPLICITY-BAND CLOSER on the (per-target × bool) column of the equivalence-partition surface, positioned as the direct MULTIPLICITY-BAND projection of the Self::count_occurrences_of per-target multiplicity primitive one MULTIPLICITY-BAND axis over from BOTH the (per-target × bool) MULTIPLICITY-POSITIVE corner Self::occurs_in (mult > 0) AND the (per-target × bool) MULTIPLICITY-EQUALS-ONE corner Self::is_unique_occurrence_of (mult == 1). The three bands (== 0, == 1, >= 2) partition the per-target multiplicity axis exhaustively into three disjoint arms, exposed on the trait through the disjoint predicate triple (!occurs_in, is_unique_occurrence_of, is_repeated_occurrence_of) that closes the (per-target × bool × multiplicity-band) 3-corner face on the equivalence-partition surface — every position on the per-target multiplicity axis binds to exactly ONE of the three typed predicates.

fn is_saturated_by(target: Self, items: &[Self]) -> bool

The N-ARY ORDERING-AGNOSTIC “target saturates every position” predicate — true iff every position of items sits at the target variant, computed as the strict-equality test of the per-target multiplicity primitive Self::count_occurrences_of against the slice arity items.len(). The PER-TARGET × bool × per-position-universal-quantifier corner OPENING the (per-target × bool × per-position-quantifier) 2-corner face on the equivalence-partition surface at the ∀-arm peer to the pre- existing (per-target × bool × per-position-EXISTENTIAL-quantifier) Self::occurs_in ∃-arm one QUANTIFIER-axis over — the ∃/∀ duality on the PER-POSITION quantifier axis at the SAME per- target arity. Distinct from the (per-target × bool × multiplicity-band) trichotomy corners Self::occurs_in (mult > 0) / Self::is_unique_occurrence_of (mult == 1) / Self::is_repeated_occurrence_of (mult >= 2) which sit on the multiplicity-band axis, while this predicate sits on the slice-arity-relative saturation axis (multiplicity == items.len()).

fn variant_counts(items: &[Self]) -> Vec<usize>

The N-ARY ORDERING-AGNOSTIC “per-slot variant histogram” projection — the Vec<usize> DECLARATION-ORDER histogram over Self::ALL whose slot i reports the multiplicity of T::ALL[i] in items. The Vec<usize> per-slot histogram opener on the (per-target × Vec) column of the equivalence- partition surface, positioned as the concrete AGGREGATION behind the just-lifted usize-return Self::count_occurrences_of per-target multiplicity primitive (which reports the multiplicity of ONE target) and the Vec-return Self::present_variants present-witness projection (which reports the STRICTLY-POSITIVE arm of the same histogram as a typed variant witness). The (per-target, per-slot) × (usize, Vec) 2×2 = 4-corner (arity × return-shape) face on the equivalence-partition surface now closes the Vec<usize> per- slot column at the (Vec, per-slot) corner peer to the (usize, per-target) corner Self::count_occurrences_of opened.

fn sorted_variant_counts(items: &[Self]) -> Vec<usize>

The N-ARY ORDERING-AGNOSTIC “per-slot variant histogram” projection in LEX order — the Vec<usize> LEX-ORDER histogram over Self::sorted_variants whose slot i reports the multiplicity of T::sorted_variants()[i] in items. The LEX-ORDER peer of Self::variant_counts on the (declaration, lex) ordering axis of the (per-slot × Vec) column of the equivalence-partition surface — closes the lex arm past the declaration arm the sibling Self::variant_counts opened. The (per-slot × Vec) × (declaration, lex) 1×2 = 2-corner (return-shape × ordering) face on the histogram surface now closes at BOTH ordering corners.

fn max_variant_count(items: &[Self]) -> usize

The N-ARY ORDERING-AGNOSTIC “modal multiplicity” projection — the usize MAX-BAR of Self::variant_counts, reporting the largest per-variant occurrence count across Self::ALL, or 0 when items is empty. The SCALAR-STATISTIC opener on the (set-level × usize × statistical-aggregate) column of the equivalence-partition surface — the FIRST typed set-level scalar aggregate to reduce the Self::variant_counts Vec<usize> histogram to a single usize bar-height statistic past the pre-existing (set-level × usize × cardinality) column of Self::count_distinct + Self::count_missing (which count slots of the histogram — the count of non-zero bars and the count of zero bars — rather than the bars’ magnitudes).

fn min_variant_count(items: &[Self]) -> usize

The N-ARY ORDERING-AGNOSTIC “least-common multiplicity” projection — the usize MIN-BAR of Self::variant_counts, reporting the smallest per-variant occurrence count across Self::ALL, or 0 when items is empty. The SCALAR-STATISTIC closer on the (min-bar, max-bar) direction axis of the (set-level × usize × statistical-aggregate) column of the equivalence-partition surface, positioned as the DIRECT (min-bar) PEER to the just-lifted (max-bar) corner Self::max_variant_count. The (min-bar, max-bar) direction axis of the statistical-aggregate column now closes at both corners: the max-bar reports the LARGEST per-variant occurrence count (the modal multiplicity), and this min-bar reports the SMALLEST per-variant occurrence count (the least-common multiplicity).

fn variant_count_range(items: &[Self]) -> (usize, usize)

The N-ARY ORDERING-AGNOSTIC “variant-count range” projection — the (usize, usize) PAIR of the histogram’s (min-bar, max-bar) endpoints projected onto the trait surface as ONE call. The PAIR-RETURN endpoint-anchor opener on the (set-level × statistical-aggregate) column of the equivalence-partition surface, positioned as the direct TUPLE-RETURN peer to the two just-closed scalar-return direction corners Self::min_variant_count + Self::max_variant_count one return-shape axis over. The (set-level × statistical-aggregate) × (usize-scalar, (usize, usize)-pair) 2-corner return-shape face on the equivalence-partition surface now opens the pair- return endpoint-anchor column past the (min-bar) + (max-bar) scalar corners.

fn is_uniform(items: &[Self]) -> bool

The N-ARY ORDERING-AGNOSTIC “uniform histogram” predicate — true iff every per-variant occurrence count in items coincides at ONE scalar bar-height, computed as the just- lifted pair-return Self::variant_count_range projection’s two direction endpoints agreeing byte-for-byte. The BOOL- RETURN UNIFORMITY closer on the (set-level × statistical- aggregate) row of the equivalence-partition surface, positioned as the direct SCALAR-REDUCTION of the just-opened pair-return endpoint-anchor corner Self::variant_count_range through the (slot-0 == slot-1) tuple-projection equality. The (set-level × statistical- aggregate) × (usize-scalar, (usize, usize)-pair, bool-scalar) 3-corner return-shape face on the equivalence- partition surface now closes the bool-return uniformity column past the two scalar direction corners Self::min_variant_count + Self::max_variant_count and past the pair-return endpoint-anchor corner Self::variant_count_range, packaging the histogram’s (min-bar == max-bar) degeneracy-check as ONE bool.

fn variant_count_span(items: &[Self]) -> usize

The N-ARY ORDERING-AGNOSTIC “variant count span” projection — the usize NON-NEGATIVE scalar-difference of the just-lifted pair-return Self::variant_count_range projection’s two direction endpoints, computed as max_bar - min_bar on the (max-bar, min-bar) pair. The SCALAR-DIFFERENCE range-width opener on the (set-level × statistical-aggregate) row of the equivalence-partition surface, positioned as the second SCALAR REDUCTION of the just-opened pair-return endpoint- anchor corner Self::variant_count_range through the (slot-1 - slot-0) tuple-projection SATURATED DIFFERENCE (the pair-return corner pins slot-0 <= slot-1 by clause (102)’s direction-axis-order arm, so the difference is non-negative and no saturation ever fires). Peer posture to Self::is_uniform one return-shape axis over: the bool- return uniformity corner reduces the pair through slot-EQUALITY (min == max), yielding a bare bool; this usize-return span corner reduces the SAME pair through slot-SUBTRACTION (max - min), yielding a bare usize range-width. The (set-level × statistical-aggregate) × (usize-scalar-direction, (usize, usize)-pair, bool-scalar, usize-scalar-difference) 4-corner return- shape face on the equivalence-partition surface now opens its FOURTH corner as the direct SCALAR-DIFFERENCE reduction of the pair-return corner past the two direction corners, the pair-return corner, and the bool-return uniformity corner.

fn modal_variant(items: &[Self]) -> Option<Self>

The N-ARY ORDERING-AGNOSTIC “modal variant” projection — the Option<Self> DECLARATION-ORDER-FIRST ARGMAX over the Self::variant_counts histogram, reporting the FIRST variant of Self::ALL (walked in declaration order) whose per-target count equals Self::max_variant_count, or None when items is empty. The ARGMAX-VARIANT opener on the (set-level × Option<Self> × statistical-aggregate) column of the equivalence-partition surface, positioned as the FIRST typed Option<Self>-return aggregate past the (set-level × usize × statistical-aggregate) direction column (Self::max_variant_count, Self::min_variant_count), the (set-level × (usize, usize) × pair-endpoint) column (Self::variant_count_range), the (set- level × bool × uniformity) column (Self::is_uniform), and the (set-level × usize × scalar-difference) column (Self::variant_count_span). Where the scalar-return corners project the histogram’s MAGNITUDES (max-bar, min-bar, range, span) or the FLATNESS witness (uniformity), this projection promotes the ARGUMENT — the substrate variant achieving the max-bar — from an inline T::ALL.iter().find(|&&v| T::count_occurrences_of(v, items) == T::max_variant_count(items)) .copied() sweep at every prospective downstream “which variant is the histogram’s peak?” site to a typed Option<Self>-return primitive on the trait. Not a fresh substrate primitive on the index axis — the projection emerges from ONE T::ALL.iter().find(|&&v| ...) sweep whose predicate binds Self::count_occurrences_of against the just-lifted Self::max_variant_count scalar, guarded by an empty-slice short-circuit that maps &[] to None past the (max == 0, every-count == 0) degenerate arm where an ungauded sweep would silently return Some(T::ALL[0]).

fn sorted_modal_variant(items: &[Self]) -> Option<Self>

The N-ARY ORDERING-AGNOSTIC “sorted modal variant” projection — the Option<Self> LEX-ORDER-FIRST ARGMAX over the Self::variant_counts histogram, reporting the FIRST variant of Self::sorted_variants (walked in lex order) whose per- target count equals Self::max_variant_count, or None when items is empty. The LEX-ORDER peer of Self::modal_variant on the (declaration, lex) ordering axis of the (set-level × Option<Self> × statistical-aggregate) column — closes the lex arm past the declaration arm the sibling Self::modal_variant opened. Where Self::modal_variant walks Self::ALL in DECLARATION order and commits at the first tied argmax, this projection walks Self::sorted_variants in LEX order and commits at the first tied argmax under the ASCII-sort_unstable discriminator. The two projections AGREE byte-for-byte on every slice whose argmax is UNIQUE (a single variant achieves the modal multiplicity) AND on every slice whose argmax ties SIT ENTIRELY within the (declaration-order-first == lex-order-first) tie-break agreement window; they BIFURCATE at the smallest slice whose argmax ties spread across a (T::first() != T::sorted_first()) declaration/lex divergence. Not a fresh substrate primitive on the index axis — the projection emerges from ONE sorted_variants().into_iter().find(|&v| ...) sweep whose predicate binds Self::count_occurrences_of against the just-lifted Self::max_variant_count scalar, guarded by an empty-slice short-circuit that maps &[] to None past the (max == 0, every-count == 0) degenerate arm where an unguarded sweep would silently return Some(T::sorted_first()).

fn antimodal_variant(items: &[Self]) -> Option<Self>

The N-ARY ORDERING-AGNOSTIC “antimodal variant” projection — the Option<Self> DECLARATION-ORDER-FIRST ARGMIN over the Self::variant_counts histogram, reporting the FIRST variant of Self::ALL (walked in declaration order) whose per-target count equals Self::min_variant_count, or None when items is empty. The DIRECTION-AXIS peer of Self::modal_variant on the (max-bar, min-bar) direction axis of the (set-level × Option<Self> × statistical-aggregate) column — opens the argmin arm past the argmax arm the sibling Self::modal_variant closed on the declaration-order corner. Where Self::modal_variant finds the variant achieving Self::max_variant_count, this projection finds the variant achieving Self::min_variant_count. On any slice with a missing variant (equivalently, Self::is_missing_any holds, equivalently, min == 0), the antimodal points at a MISSING witness; on a covering slice (min ≥ 1), the antimodal points at the least-common PRESENT variant. Not a fresh substrate primitive on the index axis — the projection emerges from ONE T::ALL.iter().copied().find(|&v| ...) sweep whose predicate binds Self::count_occurrences_of against the just-lifted Self::min_variant_count scalar, guarded by an empty-slice short-circuit that maps &[] to None past the (min == 0, every-count == 0) degenerate arm where an unguarded sweep would silently return Some(T::first()).

fn sorted_antimodal_variant(items: &[Self]) -> Option<Self>

The N-ARY ORDERING-AGNOSTIC “sorted antimodal variant” projection — the Option<Self> LEX-ORDER-FIRST ARGMIN over the Self::variant_counts histogram, reporting the FIRST variant of Self::sorted_variants (walked in lex order) whose per-target count equals Self::min_variant_count, or None when items is empty. The ORDERING-AXIS peer of Self::antimodal_variant on the (declaration, lex) ordering axis of the (set-level × Option<Self> × statistical-aggregate × direction) column — CLOSES the (direction × ordering) 4-corner face at its final (argmin, lex) corner past the argmax arm the sibling Self::sorted_modal_variant closed one direction-axis over. Where Self::antimodal_variant finds the DECLARATION-ORDER-FIRST variant achieving Self::min_variant_count, this projection finds the LEX-ORDER-FIRST variant achieving Self::min_variant_count. On any slice with a missing variant (equivalently, Self::is_missing_any holds, equivalently, min == 0), the sorted-antimodal points at the lex-order-first MISSING witness; on a covering slice (min ≥ 1), the sorted-antimodal points at the lex-order-first least-common PRESENT variant. Not a fresh substrate primitive on the index axis — the projection emerges from ONE T::sorted_variants().into_iter().find(|&v| ...) sweep whose predicate binds Self::count_occurrences_of against Self::min_variant_count, guarded by an empty-slice short-circuit that maps &[] to None past the (min == 0, every-count == 0) degenerate arm where an unguarded sweep would silently return Some(T::sorted_first()).

fn modal_variants(items: &[Self]) -> Vec<Self>

The N-ARY ORDERING-AGNOSTIC “modal variants” projection — the Vec<Self> DECLARATION-ORDER witness-collection of EVERY variant of Self::ALL whose per-target count equals Self::max_variant_count, preserving Self::ALL’s declaration order and returning the empty vector when items is empty. The Vec-RETURN opener on the (set-level × Vec<Self> × statistical-aggregate × direction × argmax) corner peer to the (set-level × Option<Self> × statistical- aggregate × direction × argmax) Self::modal_variant corner one RETURN-SHAPE axis over — while Self::modal_variant reports the FIRST tied argmax variant (a single-witness commit), this projection reports EVERY tied argmax variant (a COMPLETE witness-collection, no tie-break choice). The (set- level × {Option<Self>, Vec<Self>} × statistical-aggregate × argmax × declaration-order) 2-corner (return-shape) row on the equivalence-partition surface now closes the Vec<Self> per- direction column past the Option<Self> first-witness column Self::modal_variant closed.

fn sorted_modal_variants(items: &[Self]) -> Vec<Self>

The N-ARY ORDERING-AGNOSTIC “sorted modal variants” projection — the Vec<Self> LEX-ORDER witness-collection of EVERY variant of Self::sorted_variants whose per-target count equals Self::max_variant_count, preserving Self::sorted_variants’s canonical ASCII-lex order and returning the empty vector when items is empty. The LEX-ORDER peer of Self::modal_variants one ORDERING axis over, CLOSING the (set-level × Vec<Self> × statistical-aggregate × argmax × ordering) 2-corner face at its lex-arm past the declaration-arm the sibling Self::modal_variants opened. One RETURN-SHAPE axis over from Self::sorted_modal_variant (Option<Self> first-witness under the lex tie-break): while Self::sorted_modal_variant reports the FIRST tied argmax variant walked in lex order, this projection reports EVERY tied argmax variant walked in lex order — a COMPLETE witness- collection with a canonical alphabetic display order, no tie- break choice. Not a fresh substrate primitive on the index axis — the projection emerges from ONE T::sorted_variants().into_iter().filter(|&v| T::count_occurrences_of(v, items) == T::max_variant_count(items)) .collect() sweep whose predicate binds Self::count_occurrences_of against the just-lifted Self::max_variant_count scalar, guarded by an empty-slice short-circuit that maps &[] to Vec::new() past the (max == 0, every-count == 0) degenerate arm where an unguarded sweep would silently return T::sorted_variants().

fn antimodal_variants(items: &[Self]) -> Vec<Self>

The N-ARY ORDERING-AGNOSTIC “antimodal variants” projection — the Vec<Self> DECLARATION-ORDER witness-collection of EVERY variant of Self::ALL whose per-target count equals Self::min_variant_count, preserving Self::ALL’s canonical declaration order and returning the empty vector when items is empty. The DIRECTION-ANCHOR ARGMIN peer of Self::modal_variants one DIRECTION axis over, OPENING the argmin arm of the (set-level × Vec<Self> × statistical-aggregate × direction) column past the argmax arm the sibling Self::modal_variants opened. One RETURN-SHAPE axis over from Self::antimodal_variant (Option<Self> first-witness under the declaration tie-break): while Self::antimodal_variant reports the FIRST tied argmin variant walked in declaration order, this projection reports EVERY tied argmin variant walked in declaration order — a COMPLETE witness-collection with the canonical authoring order, no tie-break choice. Not a fresh substrate primitive on the index axis — the projection emerges from ONE T::ALL.iter().copied().filter(|&v| T::count_occurrences_of(v, items) == T::min_variant_count(items)) .collect() sweep whose predicate binds Self::count_occurrences_of against the just-lifted Self::min_variant_count scalar, guarded by an empty-slice short-circuit that maps &[] to Vec::new() past the (min == 0, every-count == 0) degenerate arm where an unguarded sweep would silently return T::ALL.to_vec().

fn sorted_antimodal_variants(items: &[Self]) -> Vec<Self>

The N-ARY ORDERING-AGNOSTIC “sorted antimodal variants” projection — the Vec<Self> LEX-ORDER witness-collection of EVERY variant of Self::sorted_variants whose per-target count equals Self::min_variant_count, preserving Self::sorted_variants’s canonical ASCII-lex order and returning the empty vector when items is empty. The FINAL corner CLOSING the (return-shape × direction × ordering) 2×2×2 = 8-corner cube at its (Vec, argmin, lex) corner. The LEX-ORDER peer of Self::antimodal_variants one ORDERING axis over on the argmin arm — peer to Self::sorted_modal_variants one DIRECTION axis over on the lex-ordering arm. One RETURN-SHAPE axis over from Self::sorted_antimodal_variant (Option<Self> first-witness under the lex tie-break): while Self::sorted_antimodal_variant reports the FIRST tied argmin variant walked in lex order, this projection reports EVERY tied argmin variant walked in lex order — a COMPLETE witness-collection with a canonical alphabetic display order, no tie-break choice. Not a fresh substrate primitive on the index axis — the projection emerges from ONE T::sorted_variants().into_iter().filter(|&v| T::count_occurrences_of(v, items) == T::min_variant_count(items)) .collect() sweep whose predicate binds Self::count_occurrences_of against the just-lifted Self::min_variant_count scalar, guarded by an empty-slice short-circuit that maps &[] to Vec::new() past the (min == 0, every-count == 0) degenerate arm where an unguarded sweep would silently return T::sorted_variants().

fn count_modal_variants(items: &[Self]) -> usize

The N-ARY ORDERING-AGNOSTIC “how many variants tie for the mode?” cardinality-count projection — the usize SET-LEVEL count of variants of Self::ALL whose per-target multiplicity in items equals Self::max_variant_count, computed as the filter-count reduction over Self::ALL of the (count(v) == max) direction-anchor predicate. The USIZE-RETURN OPENER on the (set- level × usize × statistical-aggregate × direction × argmax) cardinality-count corner peer to the (set-level × Vec<Self> × statistical-aggregate × direction × argmax) Self::modal_variants complete-witness corner one RETURN-SHAPE axis over on the modal- aggregation matrix (Vec<Self> witness → usize cardinality via the trivial .len() sharpening) AND peer to the (set-level × usize × multiplicity-band == 1) Self::count_unique_variants and (set-level × usize × multiplicity-band >= 2) Self::count_repeating_variants and (set-level × usize × multiplicity-band == 0) Self::count_missing cardinality- count corners one AGGREGATION-KIND axis over on the (set-level × usize) row of the equivalence-partition surface (multiplicity- band → direction-anchor aggregation-kind bifurcation). Not a fresh substrate primitive on the index axis — the count emerges from one is_empty()-guarded filter-count reduction over Self::ALL of the (count(v) == max) predicate against the just-lifted Self::max_variant_count scalar, guarded by an empty-slice short-circuit that maps &[] to 0 past the (max == 0, every- count == 0) degenerate arm where an unguarded sweep would silently return Self::CARDINALITY (every variant satisfies the vacuous 0 == 0 predicate) — equivalently, the length of the just-lifted Self::modal_variants complete-witness Vec.

fn count_antimodal_variants(items: &[Self]) -> usize

The N-ARY ORDERING-AGNOSTIC “how many variants tie for the antimode?” cardinality-count projection — the usize SET-LEVEL count of variants of Self::ALL whose per-target multiplicity in items equals Self::min_variant_count, computed as the filter-count reduction over Self::ALL of the (count(v) == min) direction-anchor predicate. The USIZE-RETURN CLOSER on the (set-level × usize × statistical-aggregate × direction × argmin) cardinality-count corner CLOSING the (set- level × usize × statistical-aggregate × direction) 2-corner cardinality-count face peer to the (set-level × usize × statistical-aggregate × direction × argmax) Self::count_modal_variants cardinality-count corner one DIRECTION axis over on the modal-aggregation matrix, AND peer to the (set-level × Vec<Self> × statistical-aggregate × direction × argmin) Self::antimodal_variants complete-witness corner one RETURN-SHAPE axis over on the same direction-anchor arm (Vec<Self> witness → usize cardinality via the trivial .len() sharpening). Not a fresh substrate primitive on the index axis — the count emerges from one is_empty()-guarded filter-count reduction over Self::ALL of the (count(v) == min) predicate against the just-lifted Self::min_variant_count scalar, guarded by an empty-slice short-circuit that maps &[] to 0 past the (min == 0, every- count == 0) degenerate arm where an unguarded sweep would silently return Self::CARDINALITY (every variant satisfies the vacuous 0 == 0 predicate) — equivalently, the length of the just-lifted Self::antimodal_variants complete-witness Vec.

fn is_modal_variant_of(target: Self, items: &[Self]) -> bool

The N-ARY ORDERING-AGNOSTIC “target is a modal variant” per-target predicate — true iff target’s per-target multiplicity in items coincides with Self::max_variant_count AND items is non-empty, computed as the conjunction of the non-emptiness guard with the strict-equality test of Self::count_occurrences_of against Self::max_variant_count. The BOOL-RETURN opener on the (per- target × bool × statistical-aggregate × direction × argmax) corner, positioned as the direct SET-LEVEL-EXISTENTIAL-LIFT INVERSE — the per-target arity peer — of the (set-level × usize × statistical- aggregate × direction × argmax) cardinality-count corner Self::count_modal_variants one ARITY axis over (set-level × usize → per-target × bool), AND the STATISTICAL-AGGREGATE peer of the pre-existing (per-target × bool × multiplicity-band == 1) Self::is_unique_occurrence_of one PREDICATE-KIND axis over (multiplicity-band → statistical-aggregate) on the same per-target bool row of the equivalence-partition surface. Not a fresh substrate primitive on the index axis — the predicate emerges from one non-emptiness guard conjoined with one strict-equality test of Self::count_occurrences_of against Self::max_variant_count, equivalently the [Vec::contains] membership of the target in the just-lifted Self::modal_variants argmax witness-collection.

fn is_antimodal_variant_of(target: Self, items: &[Self]) -> bool

The N-ARY ORDERING-AGNOSTIC “target is an antimodal variant” per- target predicate — true iff target’s per-target multiplicity in items coincides with Self::min_variant_count AND items is non-empty, computed as the conjunction of the non-emptiness guard with the strict-equality test of Self::count_occurrences_of against Self::min_variant_count. The BOOL-RETURN CLOSER on the (per-target × bool × statistical-aggregate × direction × argmin) corner CLOSING the (per-target × bool × statistical-aggregate × direction) 2-corner face at its argmin arm past the argmax corner Self::is_modal_variant_of one DIRECTION axis over, AND the direct SET-LEVEL-EXISTENTIAL-LIFT INVERSE — the per-target arity peer — of the (set-level × usize × statistical-aggregate × direction × argmin) cardinality-count corner Self::count_antimodal_variants one ARITY axis over (set-level × usize → per-target × bool). Not a fresh substrate primitive on the index axis — the predicate emerges from one non-emptiness guard conjoined with one strict-equality test of Self::count_occurrences_of against Self::min_variant_count, equivalently the [Vec::contains] membership of the target in the just-lifted Self::antimodal_variants argmin witness-collection.

fn has_unique_mode(items: &[Self]) -> bool

The N-ARY ORDERING-AGNOSTIC “does the mode fall on a UNIQUE variant?” set-level predicate — true iff EXACTLY ONE variant of Self::ALL ties for Self::max_variant_count in items, computed as the strict-equality test of the just-lifted Self::count_modal_variants cardinality-count aggregate against the scalar threshold 1. The BOOL-RETURN SHARPENING on the (set- level × bool × statistical-aggregate × direction × argmax × unique- tie) corner OPENING the (set-level × bool × statistical-aggregate × direction × argmax × cardinality-count-threshold) column peer to Self::count_modal_variants one RETURN-SHAPE axis over (set- level × usize cardinality → set-level × bool uniqueness test against 1) AND peer to Self::modal_variant one RETURN-SHAPE axis over (set-level × Option<Self> first-witness → set-level × bool uniqueness of the witness’s tie-class). Not a fresh substrate primitive on the index axis — the predicate emerges from one strict-equality test of the just-lifted Self::count_modal_variants scalar against 1, equivalently the Vec::len equality of the declaration-order argmax witness- collection Self::modal_variants against 1.

fn has_unique_antimode(items: &[Self]) -> bool

The N-ARY ORDERING-AGNOSTIC “does the antimode fall on a UNIQUE variant?” set-level predicate — true iff EXACTLY ONE variant of Self::ALL ties for Self::min_variant_count in items, computed as the strict-equality test of the just-lifted Self::count_antimodal_variants cardinality-count aggregate against the scalar threshold 1. The BOOL-RETURN SHARPENING on the (set-level × bool × statistical-aggregate × direction × argmin × unique-tie) corner CLOSING the (set-level × bool × statistical- aggregate × direction × unique-tie) 2-corner face at its argmin arm past the just-opened Self::has_unique_mode argmax corner one DIRECTION axis over on the modal-aggregation matrix, AND peer to Self::count_antimodal_variants one RETURN-SHAPE axis over (set-level × usize cardinality → set-level × bool uniqueness test against 1) AND peer to Self::antimodal_variant one RETURN-SHAPE axis over (set-level × Option<Self> first-witness → set-level × bool uniqueness of the witness’s tie-class). Not a fresh substrate primitive on the index axis — the predicate emerges from one strict-equality test of the just-lifted Self::count_antimodal_variants scalar against 1, equivalently the Vec::len equality of the declaration-order argmin witness-collection Self::antimodal_variants against 1.

fn is_unique_modal_variant_of(target: Self, items: &[Self]) -> bool

The N-ARY ORDERING-AGNOSTIC “target is THE UNIQUE modal variant” per- target predicate — true iff target is a modal variant of items (its per-target multiplicity coincides with Self::max_variant_count) AND items has a unique mode (Self::count_modal_variants == 1), computed as the conjunction of the just-lifted per-target argmax membership predicate Self::is_modal_variant_of with the just- lifted set-level modal-uniqueness predicate Self::has_unique_mode. The BOOL-RETURN ARITY-LIFT opener on the (per-target × bool × statistical-aggregate × direction × argmax × unique-tie) corner OPENING the (arity × unique-tie) 2-corner face at its (per-target × argmax) arm peer to Self::has_unique_mode (set-level × bool × argmax × unique-tie) one ARITY axis over AND peer to Self::is_modal_variant_of (per-target × bool × argmax) one UNIQUE-TIE-SHARPENING axis over. Not a fresh substrate primitive on the index axis — the predicate emerges from the conjunction of the per-target argmax membership predicate with the set-level modal- uniqueness scalar, equivalently the strict-equality test of the just-lifted first-witness Self::modal_variant projection against Some(target).

fn is_unique_antimodal_variant_of(target: Self, items: &[Self]) -> bool

The N-ARY ORDERING-AGNOSTIC “target is THE UNIQUE antimodal variant” per-target predicate — true iff target is an antimodal variant of items (its per-target multiplicity coincides with Self::min_variant_count) AND items has a unique antimode (Self::count_antimodal_variants == 1), computed as the conjunction of the just-lifted per-target argmin membership predicate Self::is_antimodal_variant_of with the just-lifted set-level antimodal-uniqueness predicate Self::has_unique_antimode. The BOOL-RETURN DIRECTION-CLOSING corner CLOSING the (per-target × bool × statistical-aggregate × direction × unique-tie) 2-corner face at its argmin arm peer to Self::is_unique_modal_variant_of one DIRECTION axis over AND peer to Self::has_unique_antimode (set-level × bool × argmin × unique-tie) one ARITY axis over AND peer to Self::is_antimodal_variant_of (per-target × bool × argmin) one UNIQUE-TIE-SHARPENING axis over. Not a fresh substrate primitive on the index axis — the predicate emerges from the conjunction of the per-target argmin membership predicate with the set-level antimodal-uniqueness scalar, equivalently the strict-equality test of the just-lifted first-witness Self::antimodal_variant projection against Some(target).

fn unique_modal_variant(items: &[Self]) -> Option<Self>

The N-ARY ORDERING-AGNOSTIC “THE unique modal variant” projection — Some(v) iff items has a unique mode (Self::has_unique_mode holds) AND v is the sole variant achieving Self::max_variant_count, else None. Computed as the just-lifted set-level modal-uniqueness bit Self::has_unique_mode guarding the just-lifted declaration- order first-witness Self::modal_variant projection: when the guard holds the argmax witness is unambiguous and lifted verbatim; when the guard falsifies the projection collapses to None. The Option<Self>-RETURN SHARPENING on the (set-level × Option<Self> × statistical-aggregate × direction × argmax × unique-tie) corner OPENING the (set-level × Option<Self> × statistical-aggregate × unique-tie) column past the four (set-level × Option<Self> × statistical-aggregate × direction × ordering) declaration/lex/ argmax/argmin unsharpened corners (Self::modal_variant, Self::sorted_modal_variant, Self::antimodal_variant, Self::sorted_antimodal_variant) one UNIQUE-TIE-SHARPENING axis over on the modal-aggregation matrix, AND peer to Self::has_unique_mode one RETURN-SHAPE axis over (set-level × bool uniqueness bit → set-level × Option<Self> witness-when- unique) AND peer to Self::modal_variant one UNIQUE-TIE- SHARPENING axis over (declaration-order first-witness → declaration- order first-witness gated by uniqueness). Not a fresh substrate primitive on the index axis — the projection emerges from a boolean conjunction of the just-lifted set-level uniqueness bit with the just-lifted declaration-order first-witness projection under an Option-collapse when the guard falsifies.

fn sorted_unique_modal_variant(items: &[Self]) -> Option<Self>

The N-ARY ORDERING-AGNOSTIC “THE unique modal variant, lex-first” projection — Some(v) iff items has a unique mode (Self::has_unique_mode holds) AND v is the sole variant of Self::sorted_variants achieving Self::max_variant_count, else None. Computed as the just-lifted set-level modal- uniqueness bit Self::has_unique_mode guarding a LEX-ORDER first-witness sweep of Self::sorted_variants keyed on count == max — equivalently, the just-lifted Self::sorted_modal_variant projection under the same guard. The LEX-ORDER Option<Self>-RETURN UNIQUE-TIE SHARPENING corner OPENING the (set-level × Option<Self> × sorted × statistical- aggregate × direction × argmax × unique-tie) row on the MODAL- AGGREGATION surface — the lex-ordering peer of the just-lifted declaration-order Self::unique_modal_variant one ORDERING axis over, peer to Self::sorted_modal_variants one UNIQUE- TIE-SHARPENING axis over (existential >= 1 Vec of modal witnesses → uniqueness == 1 Option<Self> collapse), AND peer to Self::sorted_unique_missing_variant + Self::sorted_unique_repeating_variant + Self::sorted_unique_unique_variant one SURFACE axis over on the equivalence-partition matrix. Not a fresh substrate primitive on the index axis — the projection emerges from a boolean conjunction of the set-level modal-uniqueness bit with a lex-order first-witness Iterator::find sweep of Self::sorted_variants under an Option-collapse when the guard falsifies.

fn unique_antimodal_variant(items: &[Self]) -> Option<Self>

The N-ARY ORDERING-AGNOSTIC “THE unique antimodal variant” projection — Some(v) iff items has a unique antimode (Self::has_unique_antimode holds) AND v is the sole variant achieving Self::min_variant_count, else None. Computed as the just-lifted set-level antimodal-uniqueness bit Self::has_unique_antimode guarding the declaration-order first- witness Self::antimodal_variant projection: when the guard holds the argmin witness is unambiguous and lifted verbatim; when the guard falsifies the projection collapses to None. The Option<Self>- RETURN SHARPENING on the (set-level × Option<Self> × statistical- aggregate × direction × argmin × unique-tie) corner CLOSING the (set-level × Option<Self> × statistical-aggregate × direction × unique-tie) 2-corner face at its argmin arm past the just-opened Self::unique_modal_variant argmax corner one DIRECTION axis over on the modal-aggregation matrix, AND peer to Self::has_unique_antimode one RETURN-SHAPE axis over (set-level × bool uniqueness bit → set-level × Option<Self> witness-when- unique) AND peer to Self::antimodal_variant one UNIQUE-TIE- SHARPENING axis over (declaration-order first-witness → declaration- order first-witness gated by uniqueness). Not a fresh substrate primitive on the index axis — the projection emerges from a boolean conjunction of the just-lifted set-level antimodal-uniqueness bit with the just-lifted declaration-order first-argmin witness projection under an Option-collapse when the guard falsifies.

fn sorted_unique_antimodal_variant(items: &[Self]) -> Option<Self>

The N-ARY ORDERING-AGNOSTIC “THE unique antimodal variant, lex- first” projection — Some(v) iff items has a unique antimode (Self::has_unique_antimode holds) AND v is the sole variant of Self::sorted_variants achieving Self::min_variant_count, else None. Computed as the just-lifted set-level antimodal- uniqueness bit Self::has_unique_antimode guarding a LEX-ORDER first-witness sweep of Self::sorted_variants keyed on count == min — equivalently, the just-lifted Self::sorted_antimodal_variant projection under the same guard. The LEX-ORDER Option<Self>-RETURN UNIQUE-TIE SHARPENING corner EXHAUSTIVELY CLOSING the (set-level × Option<Self> × statistical-aggregate × direction × ordering × unique-tie) 2×2×2 = 8-corner cube at its FINAL corner past the (argmax, declaration) Self::unique_modal_variant opener, the (argmax, lex) Self::sorted_unique_modal_variant just-lifted argmax-lex closure, and the (argmin, declaration) Self::unique_antimodal_variant argmin-declaration closure — the argmin-lex arm one ORDERING axis over from Self::unique_antimodal_variant AND one DIRECTION axis over from Self::sorted_unique_modal_variant. Not a fresh substrate primitive on the index axis — the projection emerges from a boolean conjunction of the set-level antimodal-uniqueness bit with a lex-order first-witness Iterator::find sweep of Self::sorted_variants under an Option-collapse when the guard falsifies.

fn sorted_unique_extremal_variant(items: &[Self]) -> Option<Self>

The N-ARY ORDERING-AGNOSTIC “THE unique extremal variant, lex- first” projection — Some(v) iff items has a UNIQUE extremal witness (Self::has_unique_extremal_variant holds) AND v is the sole variant of Self::sorted_variants achieving EITHER Self::max_variant_count OR Self::min_variant_count, else None. Computed as the just-lifted set-level extremal-union uniqueness bit Self::has_unique_extremal_variant guarding a LEX-ORDER first-witness sweep of Self::sorted_variants keyed on count == max || count == min — equivalently, the just- lifted Self::sorted_extremal_variant projection under the same guard. The LEX-ORDER Option<Self>-RETURN UNIQUE-TIE SHARPENING corner OPENING the (set-level × Option<Self> × statistical-aggregate × direction-composition × ordering × unique-tie) column past the (declaration, union) opener Self::unique_extremal_variant one ORDERING axis over on the modal-aggregation matrix — the union-lex arm one COMBINATOR axis over from Self::sorted_unique_modal_variant / Self::sorted_unique_antimodal_variant which just closed the direction-anchored 8-corner cube at the (argmax, lex) and (argmin, lex) corners. Not a fresh substrate primitive on the index axis — the projection emerges from a boolean conjunction of the set-level extremal-union uniqueness bit with a lex-order first-witness Iterator::find sweep of Self::sorted_variants under an Option-collapse when the guard falsifies.

fn sorted_unique_middle_band_variant(items: &[Self]) -> Option<Self>

The N-ARY ORDERING-AGNOSTIC “THE unique middle-band variant, lex- first” projection — Some(v) iff items has a UNIQUE strict- interior witness (Self::has_unique_middle_band_variant holds) AND v is the sole variant of Self::sorted_variants with occurrence-count STRICTLY BETWEEN Self::max_variant_count AND Self::min_variant_count, else None. Computed as the just- lifted set-level middle-band uniqueness bit Self::has_unique_middle_band_variant guarding the LEX-ORDER strict-interior first-witness Self::sorted_middle_band_variant projection: when the guard holds the complement witness is unambiguous and lifted verbatim; when the guard falsifies the projection collapses to None. The LEX-ORDER Option<Self>- RETURN UNIQUE-TIE SHARPENING corner CLOSING the complement arm of the (set-level × sorted × Option<Self> × direction- composition × combinator × unique-tie) row past the just-opened UNION arm Self::sorted_unique_extremal_variant one COMBINATOR axis over on the modal-aggregation matrix AND peer to Self::unique_middle_band_variant one ORDERING axis over (declaration-order → lex-order strict-interior first-witness- when-unique) AND peer to Self::sorted_middle_band_variant one UNIQUE-TIE-SHARPENING axis over (unsharpened lex-order strict-interior first-witness → uniqueness-gated lex-order strict-interior first-witness). Not a fresh substrate primitive on the index axis — the projection emerges from a boolean conjunction of the just-lifted set-level middle-band uniqueness bit with the just-lifted lex-order strict-interior first-witness projection under an Option-collapse when the guard falsifies.

fn sorted_unique_bimodal_variant(items: &[Self]) -> Option<Self>

The N-ARY ORDERING-AGNOSTIC “THE unique bimodal variant, lex- first” projection — Some(v) iff items has a UNIQUE intersection-band witness (Self::has_unique_bimodal_variant holds) AND v is the sole variant of Self::sorted_variants whose occurrence-count sits at BOTH Self::max_variant_count AND Self::min_variant_count simultaneously, else None. Computed as the just-lifted set-level bimodal uniqueness bit Self::has_unique_bimodal_variant guarding the LEX-ORDER uniformity-collapse first-witness Self::sorted_bimodal_variant projection: when the guard holds the intersection witness is unambiguous and lifted verbatim; when the guard falsifies the projection collapses to None. The LEX-ORDER Option<Self>- RETURN UNIQUE-TIE SHARPENING corner CLOSING the intersection arm of the (set-level × sorted × Option<Self> × direction- composition × combinator × unique-tie) row past the just-opened UNION arm Self::sorted_unique_extremal_variant AND the just- closed COMPLEMENT arm Self::sorted_unique_middle_band_variant one COMBINATOR axis over on the modal-aggregation matrix AND EXHAUSTIVELY CLOSING the (set-level × sorted × Option<Self> × direction-composition × combinator × ordering × unique-tie) 3×2 face at its FINAL SIXTH TILE — the (intersection, lex) corner past the (union, declaration), (union, lex), (complement, declaration), (complement, lex), (intersection, declaration) five closers. Peer to Self::unique_bimodal_variant one ORDERING axis over (declaration-order → lex-order intersection first-witness-when- unique) AND peer to Self::sorted_bimodal_variant one UNIQUE-TIE-SHARPENING axis over (unsharpened lex-order intersection first-witness → uniqueness-gated lex-order intersection first-witness). Not a fresh substrate primitive on the index axis — the projection emerges from a boolean conjunction of the just-lifted set-level bimodal uniqueness bit with the just-lifted lex-order intersection first-witness projection under an Option-collapse when the guard falsifies.

fn is_extremal_variant_of(target: Self, items: &[Self]) -> bool

The N-ARY ORDERING-AGNOSTIC “target is AT EITHER histogram extreme” per-target predicate — true iff target sits on the modal (argmax) band OR the antimodal (argmin) band of the per- variant occurrence histogram over items, computed as the DIRECTION-AGNOSTIC UNION of the just-lifted per-target argmax membership predicate Self::is_modal_variant_of with the just-lifted per-target argmin membership predicate Self::is_antimodal_variant_of under ||. The BOOL-RETURN DIRECTION-AGNOSTIC UNION OPENER on the (per-target × bool × statistical-aggregate × direction-agnostic × union) corner OPENING the (per-target × bool × statistical-aggregate × direction-composition) column past the four (per-target × bool × statistical-aggregate × direction × unsharpened/unique-tie) direction-anchored corners (Self::is_modal_variant_of, Self::is_antimodal_variant_of, Self::is_unique_modal_variant_of, Self::is_unique_antimodal_variant_of) one DIRECTION- COMPOSITION axis over on the modal-aggregation matrix. Not a fresh substrate primitive on the index axis — the predicate emerges from ONE boolean disjunction of the two direction- anchored per-target argmax/argmin membership predicates, equivalently the non-emptiness-guarded disjunction test of the just-lifted Self::count_occurrences_of scalar against EITHER Self::max_variant_count OR Self::min_variant_count.

fn is_bimodal_variant_of(target: Self, items: &[Self]) -> bool

The N-ARY ORDERING-AGNOSTIC “target at BOTH histogram extremes?” predicate — true iff target’s per-slot count in items equals BOTH Self::max_variant_count AND Self::min_variant_count simultaneously, computed as the boolean CONJUNCTION of Self::is_modal_variant_of and Self::is_antimodal_variant_of. The BOOL-RETURN closer on the (per-target × bool × statistical- aggregate × direction-composition × combinator) 2-corner face at its && CONJUNCTION arm past the just-opened || DISJUNCTION arm Self::is_extremal_variant_of one COMBINATOR axis over, AND the per-target × flat-histogram-diagonal witness on the (per-target × bool × statistical-aggregate × direction-composition) column. Not a fresh substrate primitive on the index axis — the predicate emerges from ONE boolean AND on the two just-lifted direction- anchored membership predicates, equivalently the count-band coincidence identity count(target, items) == max_variant_count(items) == min_variant_count(items) on non-empty slices (where the max/min bands COINCIDE on the flat-histogram diagonal at target).

fn count_bimodal_variants(items: &[Self]) -> usize

The N-ARY ORDERING-AGNOSTIC “how many variants sit at BOTH histogram extremes?” cardinality-count projection — the usize SET-LEVEL count of variants of Self::ALL for which Self::is_bimodal_variant_of holds against items, SHARPENED past the naive filter-count reduction over the per-target predicate via the uniformity-collapse identity: on non-empty slices EVERY variant satisfies the flat-diagonal predicate iff Self::is_uniform holds (max == min), so the count collapses to Self::CARDINALITY on flat-histogram non-empty slices and to 0 on every non-flat non- empty slice AND on the empty slice. The USIZE-RETURN CLOSER on the (set-level × usize × statistical-aggregate × direction-composition × combinator) 2-corner face at its && CONJUNCTION arm one COMBINATOR axis over from a prospective disjunction sibling count_extremal_variants, AND the direct SET-LEVEL ARITY LIFT of the just-lifted (per-target × bool × statistical-aggregate × direction-composition × intersection) Self::is_bimodal_variant_of corner one ARITY axis over on the modal-aggregation matrix, AND peer to Self::count_modal_variants one DIRECTION-COMPOSITION axis over on the (set-level × usize × statistical-aggregate) cardinality-count row (count_modal_variants — argmax filter-count; THIS — intersection scalar branch). Not a fresh substrate primitive on the index axis — the count emerges from one is_empty()-guarded scalar branch on the just-lifted Self::is_uniform projection, returning Self::CARDINALITY on flat-histogram non-empty slices and 0 otherwise. The sharpening replaces the naive T::ALL.iter().filter( |&v| T::is_bimodal_variant_of(v, items)).count() sweep (O(T::CARDINALITY² * n) — the per-target predicate itself costs O(T::CARDINALITY * n)) with a single Self::is_uniform sweep (O(T::CARDINALITY * n)), inheriting the max/min-fold cost of the underlying aggregate exactly once.

fn count_extremal_variants(items: &[Self]) -> usize

The N-ARY ORDERING-AGNOSTIC “how many variants sit at EITHER histogram extreme?” cardinality-count projection — the usize SET-LEVEL count of variants of Self::ALL for which Self::is_extremal_variant_of holds against items, SHARPENED past the naive filter-count reduction via the inclusion-exclusion identity |A ∪ B| = |A| + |B| − |A ∩ B| against the just-lifted direction-anchored cardinality-count pair Self::count_modal_variants + Self::count_antimodal_variants and the intersection sibling Self::count_bimodal_variants. The USIZE-RETURN CLOSER on the (set-level × usize × statistical-aggregate × direction-composition × combinator) 2-corner cardinality-count face at its || DISJUNCTION arm past the just-closed && CONJUNCTION arm Self::count_bimodal_variants one COMBINATOR axis over on the modal-aggregation matrix, AND the direct SET-LEVEL ARITY LIFT of the just-lifted (per-target × bool × statistical-aggregate × direction-composition × union) Self::is_extremal_variant_of corner one ARITY axis over, AND peer to Self::count_modal_variants + Self::count_antimodal_variants one COMBINATOR axis over on the (set-level × usize × statistical-aggregate × direction-composition) cardinality-count row. Not a fresh substrate primitive on the index axis — the count emerges from ONE is_empty() guard + ONE inclusion-exclusion arithmetic on the three just-lifted set-level cardinality-count aggregates, replacing the naive T::ALL.iter().filter(|&v| T::is_extremal_variant_of(v, items)).count() sweep (O(T::CARDINALITY² * n) — the per-target predicate itself costs O(T::CARDINALITY * n)) with three max/min-fold sweeps (O(T::CARDINALITY * n) each) that ALREADY run inside the direction siblings, so on any callsite that also consumes Self::count_modal_variants or Self::count_antimodal_variants the arithmetic collapses to two arithmetic ops and one comparison against a cached fold pair, inheriting the max/min-fold cost of the underlying aggregates exactly once.

fn is_middle_band_variant_of(target: Self, items: &[Self]) -> bool

The N-ARY ORDERING-AGNOSTIC “target sits STRICTLY between the two histogram extremes?” predicate — true iff the slice is non-empty AND target’s per-slot count in items sits STRICTLY between Self::min_variant_count and Self::max_variant_count (equivalently, target is NEITHER at the argmax band NOR at the argmin band), computed as the boolean CONJUNCTION of a non-empty guard AND the negation of Self::is_extremal_variant_of. The BOOL-RETURN OPENER on the (per-target × bool × statistical- aggregate × direction-composition × complement) middle-band corner past the just-closed (per-target × bool × statistical-aggregate × direction-composition × combinator) 2-corner union/intersection face — the direct De Morgan COMPLEMENT of Self::is_extremal_variant_of on non-empty slices, closing the (extreme / middle) partition of Self::ALL on every non-empty slice at every target. Not a fresh substrate primitive on the index axis — the predicate emerges from ONE non-empty guard AND one boolean negation of the just- lifted (per-target × bool × direction-composition × union) Self::is_extremal_variant_of corner, equivalently the count- band strict-between test min < count < max on non-empty slices.

fn count_middle_band_variants(items: &[Self]) -> usize

The N-ARY ORDERING-AGNOSTIC “how many variants sit STRICTLY between the two histogram extremes?” cardinality-count projection — the usize SET-LEVEL count of variants of Self::ALL for which Self::is_middle_band_variant_of holds against items, SHARPENED past the naive filter-count reduction via the De Morgan complement identity |middle| = T::CARDINALITY - |extremal| on non-empty slices against the just-lifted (set-level × usize × direction- composition × union) Self::count_extremal_variants cardinality- count aggregate. The USIZE-RETURN CLOSER on the (set-level × usize × statistical-aggregate × direction-composition × complement) middle-band corner ARITY-LIFTING Self::is_middle_band_variant_of one ARITY axis over on the modal-aggregation matrix, AND the direct SET-LEVEL COMPLEMENT of the just-lifted (set-level × usize × statistical-aggregate × direction-composition × union) Self::count_extremal_variants corner one COMPLEMENT axis over, closing the (extreme / middle) partition on the set-level usize row. Not a fresh substrate primitive on the index axis — the count emerges from ONE is_empty() guard + ONE subtraction on the just- lifted set-level union cardinality-count aggregate, replacing the naive T::ALL.iter().filter(|&v| T::is_middle_band_variant_of(v, items)).count() sweep (O(T::CARDINALITY² * n) — the per-target predicate itself costs O(T::CARDINALITY * n) via the nested extremal test) with one subtraction against a cached Self::count_extremal_variants aggregate that ALREADY runs inside the union sibling, so on any callsite that also consumes Self::count_extremal_variants the arithmetic collapses to one arithmetic op against the cached fold, inheriting the max/min-fold cost of the underlying aggregate exactly once.

fn has_middle_band_variant(items: &[Self]) -> bool

The N-ARY ORDERING-AGNOSTIC “does ANY variant sit STRICTLY between the two histogram extremes?” set-level existential predicate — true iff AT LEAST ONE variant of Self::ALL carries an occurrence-count strictly greater than Self::min_variant_count AND strictly less than Self::max_variant_count, computed as the strict-lower-bound test of the just-lifted Self::count_middle_band_variants cardinality-count aggregate against the scalar threshold 1. The BOOL-RETURN OPENER on the (set-level × bool × statistical-aggregate × direction-composition × complement × existential) middle-band existence corner peer to Self::count_middle_band_variants one RETURN-SHAPE axis over (set-level × usize cardinality → set-level × bool existential lift against >= 1) AND the direct SET-LEVEL EXISTENTIAL LIFT of the (per-target × bool × statistical-aggregate × direction-composition × complement) Self::is_middle_band_variant_of corner one ARITY axis over on the modal-aggregation matrix. Not a fresh substrate primitive on the index axis — the predicate emerges from one strict-lower-bound test of the just-lifted Self::count_middle_band_variants scalar against 1, equivalently the disjunction over Self::ALL of the per-target Self::is_middle_band_variant_of predicate. Cheaper than the count on hot paths that only need an existence witness — the count aggregate’s T::CARDINALITY - count_extremal arithmetic runs unchanged, but the downstream consumer binds a typed bool bit against the composed threshold rather than a scalar-and-compare composition.

fn has_bimodal_variant(items: &[Self]) -> bool

The N-ARY ORDERING-AGNOSTIC “does ANY variant sit on the FLAT HISTOGRAM DIAGONAL?” set-level existential predicate — true iff AT LEAST ONE variant of Self::ALL carries an occurrence-count EQUAL to BOTH Self::min_variant_count AND Self::max_variant_count (equivalently, the slice is non-empty AND every variant sits at BOTH extremes simultaneously — Self::is_uniform holds on the non-empty guard), computed as the strict-lower-bound test of the just-lifted Self::count_bimodal_variants cardinality-count aggregate against the scalar threshold 1. The BOOL-RETURN CLOSER on the (set-level × bool × statistical-aggregate × direction-composition × intersection × existential) bimodal existence corner peer to Self::count_bimodal_variants one RETURN-SHAPE axis over (set-level × usize cardinality → set-level × bool existential lift against >= 1) AND the direct SET-LEVEL EXISTENTIAL LIFT of the (per-target × bool × statistical-aggregate × direction- composition × intersection) Self::is_bimodal_variant_of corner one ARITY axis over on the modal-aggregation matrix AND peer to the just-opened Self::has_middle_band_variant one DIRECTION- COMPOSITION axis over (intersection && arm vs the complement !extremal arm — jointly with Self::has_extremal_variant’s prospective union || arm the three form the set-level existential trichotomy on the modal-aggregation matrix). Not a fresh substrate primitive on the index axis — the predicate emerges from one strict-lower-bound test of the just-lifted Self::count_bimodal_variants scalar against 1, equivalently the non-empty guard AND Self::is_uniform via the uniformity- collapse identity, equivalently the disjunction over Self::ALL of the per-target Self::is_bimodal_variant_of predicate.

fn has_extremal_variant(items: &[Self]) -> bool

The N-ARY ORDERING-AGNOSTIC “does ANY variant sit at EITHER histogram extreme?” set-level existential predicate — true iff AT LEAST ONE variant of Self::ALL carries an occurrence-count EQUAL to EITHER Self::min_variant_count OR Self::max_variant_count, SHARPENED via the union-arm non- emptiness collapse: on ANY non-empty slice the argmax band is non-empty (SOME variant achieves the max count >= 1, and that variant is trivially at the argmax extreme via Self::is_modal_variant_of, so Self::is_extremal_variant_of holds on it via the disjunction arm), and the empty slice has no target to sit anywhere. The BOOL-RETURN CLOSER on the (set-level × bool × statistical- aggregate × direction-composition × union × existential) extremal existence corner peer to Self::count_extremal_variants one RETURN-SHAPE axis over (set-level × usize cardinality → set- level × bool existential lift against >= 1) AND the direct SET-LEVEL EXISTENTIAL LIFT of the (per-target × bool × statistical-aggregate × direction-composition × union) Self::is_extremal_variant_of corner one ARITY axis over on the modal-aggregation matrix AND peer to Self::has_middle_band_variant + Self::has_bimodal_variant one DIRECTION-COMPOSITION axis over — the three form the set-level existential trichotomy on the modal-aggregation matrix (union / intersection / complement of the two direction-anchored membership predicates). Not a fresh substrate primitive on the index axis — the predicate collapses to the pre-existing standard-library !<[Self]>::is_empty() slice-empty bit past a NON-EMPTINESS COLLAPSE proof; the count-composition body T::count_extremal_variants(items) >= 1 and the existential- lift body T::ALL.iter().any(|v| T::is_extremal_variant_of(v, items)) are the equivalent-but-slower canonical forms the identities pin against.

fn extremal_variants(items: &[Self]) -> Vec<Self>

The N-ARY ORDERING-AGNOSTIC “extremal variants” projection — the Vec<Self> DECLARATION-ORDER witness-collection of EVERY variant of Self::ALL for which Self::is_extremal_variant_of holds against items (equivalently, whose per-slot count equals EITHER Self::max_variant_count OR Self::min_variant_count), preserving Self::ALL’s canonical declaration order and returning the empty vector when items is empty. The DIRECTION- COMPOSITION UNION opener on the (set-level × Vec<Self> × statistical-aggregate × direction-composition × union) corner past the direction-anchored Self::modal_variants + Self::antimodal_variants pair one DIRECTION-COMPOSITION axis over. Direct SET-LEVEL ARITY LIFT of the (per-target × bool × direction-composition × union) Self::is_extremal_variant_of corner one ARITY axis over, AND peer to Self::count_extremal_variants one RETURN-SHAPE axis over (usize cardinality → Vec<Self> witness-collection). Not a fresh substrate primitive on the index axis — the projection emerges from ONE is_empty() guard AND ONE max/min-fold pair AND ONE T::CARDINALITY-bounded filter sweep whose predicate binds Self::count_occurrences_of against the pair, guarded so &[] maps to Vec::new() past the (max == min == 0, every-count == 0) degenerate arm where an unguarded sweep would silently return T::ALL.to_vec().

fn middle_band_variants(items: &[Self]) -> Vec<Self>

The N-ARY ORDERING-AGNOSTIC “middle-band variants” projection — the Vec<Self> DECLARATION-ORDER witness-collection of EVERY variant of Self::ALL for which Self::is_middle_band_variant_of holds against items (equivalently, whose per-slot count sits STRICTLY between Self::min_variant_count and Self::max_variant_count), preserving Self::ALL’s canonical declaration order and returning the empty vector when items is empty. The DIRECTION-COMPOSITION COMPLEMENT closer on the (set-level × Vec<Self> × statistical- aggregate × direction-composition × complement) corner CLOSING the (set-level × Vec<Self> × direction-composition) row past the direction-anchored Self::modal_variants + Self::antimodal_variants pair AND the just-opened UNION arm Self::extremal_variants one DIRECTION-COMPOSITION axis over. Direct SET-LEVEL ARITY LIFT of the (per-target × bool × direction-composition × complement) Self::is_middle_band_variant_of corner one ARITY axis over, AND peer to Self::count_middle_band_variants one RETURN-SHAPE axis over (usize cardinality → Vec<Self> witness-collection). Not a fresh substrate primitive on the index axis — the projection emerges from ONE is_empty() guard AND ONE max/min-fold pair AND ONE T::CARDINALITY-bounded filter sweep whose predicate binds Self::count_occurrences_of against the pair via the STRICT interior test c != max && c != min, guarded so &[] maps to Vec::new() past the (max == min == 0, every-count == 0) degenerate arm where an unguarded sweep would silently return Vec::new() for the WRONG reason (every variant is extremal on the empty slice, not middle-band).

fn sorted_middle_band_variants(items: &[Self]) -> Vec<Self>

The N-ARY LEX-ORDER “middle-band variants” projection — the Vec<Self> LEX-ORDER witness-collection of EVERY variant of Self::sorted_variants for which Self::is_middle_band_variant_of holds against items (equivalently, whose per-slot count sits STRICTLY between Self::min_variant_count and Self::max_variant_count), preserving Self::sorted_variants’s canonical ASCII-lex order and returning the empty vector when items is empty. The LEX-ORDER peer of Self::middle_band_variants one ORDERING axis over, CLOSING the (set-level × Vec<Self> × statistical- aggregate × direction-composition × complement × ordering) 2-corner face at its lex-arm past the declaration-arm the sibling Self::middle_band_variants opened. Not a fresh substrate primitive on the index axis — the projection emerges from ONE is_empty() guard + ONE max/min-fold pair + ONE T::CARDINALITY-bounded filter sweep over Self::sorted_variants whose predicate binds Self::count_occurrences_of against the pair via the STRICT interior test c != max && c != min.

fn sorted_extremal_variants(items: &[Self]) -> Vec<Self>

The N-ARY LEX-ORDER “extremal variants” projection — the Vec<Self> LEX-ORDER witness-collection of EVERY variant of Self::sorted_variants for which Self::is_extremal_variant_of holds against items (equivalently, whose per-slot count sits AT either Self::max_variant_count or Self::min_variant_count), preserving Self::sorted_variants’s canonical ASCII-lex order and returning the empty vector when items is empty. The LEX-ORDER peer of Self::extremal_variants one ORDERING axis over, CLOSING the (set-level × Vec<Self> × statistical- aggregate × direction-composition × union × ordering) 2-corner face at its lex-arm past the declaration-arm the sibling Self::extremal_variants opened. Not a fresh substrate primitive on the index axis — the projection emerges from ONE is_empty() guard + ONE max/min-fold pair + ONE T::CARDINALITY-bounded filter sweep over Self::sorted_variants whose predicate binds Self::count_occurrences_of against the pair via the UNION test c == max || c == min.

fn bimodal_variants(items: &[Self]) -> Vec<Self>

The N-ARY ORDERING-AGNOSTIC “bimodal variants” projection — the Vec<Self> DECLARATION-ORDER witness-collection of EVERY variant of Self::ALL for which Self::is_bimodal_variant_of holds against items (equivalently, whose per-slot count sits at BOTH Self::max_variant_count AND Self::min_variant_count simultaneously), preserving Self::ALL’s canonical declaration order and returning the empty vector when items is empty. The DIRECTION-COMPOSITION INTERSECTION opener on the (set-level × Vec<Self> × statistical-aggregate × direction-composition × intersection) corner OPENING the (set-level × Vec<Self> × direction-composition × combinator) 2-corner flat-diagonal face at its && CONJUNCTION arm past the just-lifted UNION arm Self::extremal_variants one COMBINATOR axis over on the modal-aggregation matrix. Direct SET-LEVEL ARITY LIFT of the (per-target × bool × direction-composition × intersection) Self::is_bimodal_variant_of corner one ARITY axis over, AND peer to Self::count_bimodal_variants one RETURN-SHAPE axis over (usize cardinality → Vec<Self> witness-collection) via the SAME uniformity-collapse SHARPENING (which cuts one algorithmic factor of T::CARDINALITY off the naive filter sweep — a two-value dichotomy over T::ALL.to_vec() / Vec::new() gated by Self::is_uniform rather than a per- target predicate re-derivation of the max and min folds).

fn sorted_bimodal_variants(items: &[Self]) -> Vec<Self>

The N-ARY LEX-ORDER “bimodal variants” projection — the Vec<Self> LEX-ORDER witness-collection of EVERY variant of Self::sorted_variants for which Self::is_bimodal_variant_of holds against items (equivalently, whose per-slot count sits at BOTH Self::max_variant_count AND Self::min_variant_count simultaneously), preserving Self::sorted_variants’s canonical ASCII-lex order and returning the empty vector when items is empty. The LEX-ORDER peer of Self::bimodal_variants one ORDERING axis over, CLOSING the (set-level × Vec<Self> × statistical-aggregate × direction-composition × intersection × ordering) 2-corner face at its lex-arm past the declaration-arm the sibling Self::bimodal_variants opened. Not a fresh substrate primitive on the index axis — the projection emerges from the SAME uniformity-collapse SHARPENING as Self::bimodal_variants (if items.is_empty() || !T::is_uniform(items) { Vec::new() } else { T::sorted_variants() }) with T::sorted_variants() in place of T::ALL.to_vec() on the uniform arm — the lex axis surfaces ONLY in the returned walk order.

fn extremal_variant(items: &[Self]) -> Option<Self>

The N-ARY DECLARATION-ORDER “extremal variant” projection — the Option<Self> DECLARATION-ORDER-FIRST-WITNESS over the direction- composition UNION of Self::max_variant_count and Self::min_variant_count, reporting the FIRST variant of Self::ALL (walked in declaration order) whose per-target count hits AT LEAST ONE of the two histogram extremes, or None when items is empty. The OPTION-RETURN opener on the direction- composition axis peer to Self::modal_variant (argmax first- witness, declaration) and Self::antimodal_variant (argmin first-witness, declaration) one DIRECTION-COMPOSITION axis over via the disjunctive extremal predicate — the (set-level × Option<Self> × statistical-aggregate × direction-composition × union) row OPENS its declaration-order first-witness corner past the direction-anchored (argmax, argmin) pair one DIRECTION- COMPOSITION axis over on the modal-aggregation matrix. Direct FIRST-WITNESS PROJECTION of the (set-level × Vec<Self> × statistical-aggregate × direction-composition × union) Self::extremal_variants corner one RETURN-SHAPE axis over (Vec<Self> witness-collection → Option<Self> first-witness), AND peer to Self::has_extremal_variant one RETURN-SHAPE axis over (bool existence → Option<Self> first-witness), AND direct SET-LEVEL ARITY LIFT of the (per-target × bool × direction- composition × union) Self::is_extremal_variant_of corner one ARITY axis over via the FIRST-witness projection over the per- target predicate. Not a fresh substrate primitive on the index axis — the projection emerges from ONE is_empty() guard AND ONE max/min-fold pair AND ONE T::CARDINALITY-bounded declaration- order find sweep whose predicate binds Self::count_occurrences_of against the pair via the union test c == max || c == min, guarded so &[] maps to None past the (max == min == 0, every-count == 0) degenerate arm where an unguarded sweep would silently return Some(T::first()) (every variant satisfies count == 0 == max == min vacuously — the WRONG structural answer past the non-emptiness precondition Self::is_extremal_variant_of carries).

fn sorted_extremal_variant(items: &[Self]) -> Option<Self>

The N-ARY ORDERING-AGNOSTIC “sorted extremal variant” projection — the Option<Self> LEX-ORDER-FIRST-WITNESS over the Self::variant_counts histogram under the DIRECTION- COMPOSITION UNION predicate, reporting the FIRST variant of Self::sorted_variants (walked in LEX order under the ASCII-sort_unstable_by_key(label) discriminator) whose per- target count equals EITHER Self::max_variant_count OR Self::min_variant_count, or None when items is empty. The LEX-ORDER peer of Self::extremal_variant on the (declaration, lex) ordering axis of the (set-level × Option<Self> × statistical-aggregate × direction-composition × union) column — CLOSES the lex arm past the declaration arm the sibling Self::extremal_variant opened, completing the (set-level × Option<Self> × direction-composition × union × ordering) 2-corner face at both corners. Where Self::extremal_variant walks Self::ALL in DECLARATION order and commits at the first variant satisfying the union predicate c == max || c == min, this projection walks Self::sorted_variants in LEX order and commits at the first variant satisfying the SAME union predicate under the ASCII- sort_unstable_by_key(label) discriminator. The two projections AGREE byte-for-byte on every implementor whose declaration order coincides with the ASCII-lex order of its labels (a common case for enums whose variants happen to be declared in alphabetically-sorted order) AND on every slice whose union band covers all of Self::ALL (the flat-histogram fixpoints T::ALL, T::ALL ++ T::ALL, &[] degenerately-empty guard, and every matching-singleton at cardinality >= 2 where every variant satisfies c == max || c == min); they BIFURCATE at the smallest slice whose union band excludes the ambient T::sorted_first() in some non-flat middle-band configuration AND whose declaration order diverges from lex order across that band. Not a fresh substrate primitive on the index axis — the projection emerges from the same is_empty() guard + max/min- fold pair + find sweep, differing only in the substrate primitive the sweep routes through (Self::sorted_variants rather than Self::ALL).

fn middle_band_variant(items: &[Self]) -> Option<Self>

The N-ARY ORDERING-AGNOSTIC “middle-band variant” projection — the Option<Self> DECLARATION-ORDER-FIRST-WITNESS over the Self::variant_counts histogram under the DIRECTION- COMPOSITION COMPLEMENT predicate, reporting the FIRST variant of Self::ALL (walked in DECLARATION order) whose per-target count sits STRICTLY between Self::min_variant_count and Self::max_variant_count (equivalently, whose count neither tops the argmax band NOR bottoms the argmin band), or None when items is empty OR every variant sits at one of the two extremes. The COMPLEMENT-arm OPENER on the (set-level × Option<Self> × direction-composition × ordering) row past the (set-level × Option<Self> × direction-composition × union × ordering) 2-corner face the (Self::extremal_variant, Self::sorted_extremal_variant) pair just closed one COMBINATOR axis over via De Morgan complement — where the union arm walks with c == max || c == min, THIS complement arm walks with c != max && c != min. Peer to Self::middle_band_variants one RETURN-SHAPE axis over (Vec<Self> → Option<Self> first-witness), peer to Self::has_middle_band_variant one RETURN-SHAPE axis over (bool → Option<Self>), peer to Self::count_middle_band_variants one RETURN-SHAPE axis over (usize → Option<Self>), and peer to Self::extremal_variant one COMBINATOR axis over (union → complement) via the STRICT interior conjunction SHARPENING the union disjunction’s OR into the complement conjunction’s AND-NOT.

fn sorted_middle_band_variant(items: &[Self]) -> Option<Self>

The N-ARY ORDERING-AGNOSTIC “sorted middle-band variant” projection — the Option<Self> LEX-ORDER-FIRST-WITNESS over the Self::variant_counts histogram under the DIRECTION- COMPOSITION COMPLEMENT predicate, reporting the FIRST variant of Self::sorted_variants (walked in LEX order under the ASCII-sort_unstable_by_key(label) discriminator) whose per- target count sits STRICTLY between Self::min_variant_count and Self::max_variant_count (equivalently, whose count neither tops the argmax band NOR bottoms the argmin band), or None when items is empty OR every variant sits at one of the two extremes. The LEX-ORDER peer of Self::middle_band_variant on the (declaration, lex) ordering axis of the (set-level × Option<Self> × statistical-aggregate × direction-composition × complement) column — CLOSES the lex arm past the declaration arm the sibling Self::middle_band_variant opened, completing the (set-level × Option<Self> × direction-composition × complement × ordering) 2-corner face at both corners. Where Self::middle_band_variant walks Self::ALL in DECLARATION order and commits at the first variant satisfying the STRICT interior conjunction c != max && c != min, this projection walks Self::sorted_variants in LEX order and commits at the first variant satisfying the SAME strict interior conjunction under the ASCII-sort_unstable_by_key(label) discriminator. The two projections AGREE byte-for-byte on every implementor whose declaration order coincides with the ASCII-lex order of its labels (a common case for enums whose variants happen to be declared in alphabetically-sorted order) AND on every slice whose middle band is EMPTY (None on both sides via the shared flat-histogram + matching-singleton None fixpoints); they BIFURCATE at the smallest slice whose middle band is non-empty AND whose declaration order diverges from lex order across that band. Not a fresh substrate primitive on the index axis — the projection emerges from the same is_empty() guard + max/min- fold pair + find sweep as the declaration-order sibling, differing only in the substrate primitive the sweep routes through (Self::sorted_variants rather than Self::ALL) AND in NOTHING else on the predicate axis.

fn bimodal_variant(items: &[Self]) -> Option<Self>

The N-ARY ORDERING-AGNOSTIC “bimodal variant” projection — the Option<Self> DECLARATION-ORDER-FIRST-WITNESS over the Self::variant_counts histogram under the DIRECTION- COMPOSITION INTERSECTION predicate, reporting the FIRST variant of Self::ALL (walked in declaration order) whose per-target count equals BOTH Self::max_variant_count AND Self::min_variant_count simultaneously (equivalently, whose count sits at the flat-diagonal collapse where max == min), or None when items is empty OR the histogram is non-flat (max != min pins a strict direction split, so NO variant hits both extremes). The DECLARATION-ORDER opener on the (set-level × Option<Self> × direction-composition × intersection × ordering) 2-corner face, OPENING the intersection arm of the (set-level × Option<Self> × direction-composition × ordering) row past the union arm the (Self::extremal_variant, Self::sorted_extremal_variant) pair closed one COMBINATOR axis over AND past the complement arm the (Self::middle_band_variant, Self::sorted_middle_band_variant) pair closed one COMBINATOR axis over via the flat-diagonal predicate c == max && c == min (equivalently max == min, the uniformity-collapse identity). Not a fresh substrate primitive on the index axis — the projection emerges from the SAME uniformity-collapse SHARPENING as Self::bimodal_variants (if items.is_empty() || !T::is_uniform(items) { None } else { T::ALL.first().copied() }) with .first().copied() in place of .to_vec() on the uniform arm — the Option<Self> first-witness projection surfaces ONLY in the truncation from the full witness collection to its declaration-order head.

fn sorted_bimodal_variant(items: &[Self]) -> Option<Self>

The N-ARY LEX-ORDER “bimodal variant” projection — the Option<Self> LEX-ORDER-FIRST-WITNESS over the Self::variant_counts histogram under the DIRECTION- COMPOSITION INTERSECTION predicate, reporting the FIRST variant of Self::sorted_variants (walked in ASCII-lex order over Self::label) whose per-target count equals BOTH Self::max_variant_count AND Self::min_variant_count simultaneously (equivalently, whose count sits at the flat- diagonal collapse where max == min), or None when items is empty OR the histogram is non-flat (max != min pins a strict direction split, so NO variant hits both extremes). The LEX-ORDER peer of Self::bimodal_variant one ORDERING axis over, CLOSING the (set-level × Option<Self> × statistical- aggregate × direction-composition × intersection × ordering) 2-corner face at its lex-arm past the declaration-arm the sibling Self::bimodal_variant opened AND CLOSING the (set- level × Option<Self> × direction-composition × combinator × ordering) 3×2 grid at its FINAL sixth tile past the (union declaration, union lex, complement declaration, complement lex, intersection declaration) 5-tile prefix the sibling projections (Self::extremal_variant, Self::sorted_extremal_variant, Self::middle_band_variant, Self::sorted_middle_band_variant, Self::bimodal_variant) covered. Not a fresh substrate primitive on the index axis — the projection emerges from the SAME uniformity-collapse SHARPENING as Self::bimodal_variant (if items.is_empty() || !T::is_uniform(items) { None } else { T::sorted_variants().first().copied() }) with T::sorted_variants().first().copied() in place of T::ALL.first().copied() on the uniform arm — the lex axis surfaces ONLY in the returned first-witness pick.

fn has_unique_middle_band_variant(items: &[Self]) -> bool

The N-ARY ORDERING-AGNOSTIC “does the STRICT-INTERIOR band fall on a UNIQUE variant?” set-level predicate — true iff EXACTLY ONE variant of Self::ALL carries an occurrence-count STRICTLY between Self::min_variant_count and Self::max_variant_count, computed as the strict-equality test of the just-lifted Self::count_middle_band_variants cardinality-count aggregate against the scalar threshold 1. The BOOL-RETURN UNIQUE-TIE SHARPENING OPENER on the (set-level × bool × statistical-aggregate × direction-composition × complement × unique-tie) corner OPENING the (set-level × bool × direction- composition × unique-tie) column past the direction-anchored (has_unique_mode, has_unique_antimode) argmax/argmin pair one DIRECTION-COMPOSITION axis over on the modal-aggregation matrix AND peer to Self::count_middle_band_variants one RETURN-SHAPE axis over (set-level × usize cardinality → set-level × bool uniqueness test against 1) AND peer to Self::has_middle_band_variant one UNIQUE-TIE-SHARPENING axis over (existential >= 1 → uniqueness == 1). Not a fresh substrate primitive on the index axis — the predicate emerges from one strict-equality test of the just-lifted Self::count_middle_band_variants scalar against 1, equivalently the Vec::len equality of the declaration-order middle-band witness-collection Self::middle_band_variants against 1.

fn has_unique_extremal_variant(items: &[Self]) -> bool

The N-ARY ORDERING-AGNOSTIC “does the EXTREMAL union band fall on a UNIQUE variant?” set-level predicate — true iff EXACTLY ONE variant of Self::ALL carries an occurrence-count MATCHING EITHER Self::max_variant_count OR Self::min_variant_count, computed as the strict-equality test of the just-lifted Self::count_extremal_variants cardinality-count aggregate against the scalar threshold 1. The BOOL-RETURN UNIQUE-TIE SHARPENING corner CLOSING the (set-level × bool × direction- composition × unique-tie) row past the just-opened Self::has_unique_middle_band_variant complement arm one COMBINATOR axis over on the modal-aggregation matrix AND peer to Self::count_extremal_variants one RETURN-SHAPE axis over (set-level × usize cardinality → set-level × bool uniqueness test against 1) AND peer to Self::has_extremal_variant one UNIQUE-TIE-SHARPENING axis over (existential >= 1 → uniqueness == 1). Not a fresh substrate primitive on the index axis — the predicate emerges from one strict-equality test of the just-lifted Self::count_extremal_variants scalar against 1, equivalently the Vec::len equality of the declaration-order union witness- collection Self::extremal_variants against 1.

fn has_unique_bimodal_variant(items: &[Self]) -> bool

The N-ARY ORDERING-AGNOSTIC “does the BIMODAL intersection band fall on a UNIQUE variant?” set-level predicate — true iff EXACTLY ONE variant of Self::ALL carries an occurrence-count MATCHING BOTH Self::max_variant_count AND Self::min_variant_count, computed as the strict-equality test of the just-lifted Self::count_bimodal_variants cardinality- count aggregate against the scalar threshold 1. The BOOL-RETURN UNIQUE-TIE SHARPENING corner CLOSING the (set-level × bool × direction-composition × unique-tie) row past the just-lifted Self::has_unique_extremal_variant union arm one COMBINATOR axis over on the modal-aggregation matrix AND EXHAUSTIVELY CLOSING the (set-level × bool × direction-composition × combinator × unique-tie) row at its FINAL THIRD tile (past the UNION arm Self::has_unique_extremal_variant closed and the COMPLEMENT arm Self::has_unique_middle_band_variant closed). Peer to Self::count_bimodal_variants one RETURN-SHAPE axis over (set-level × usize cardinality → set-level × bool uniqueness test against 1) AND peer to Self::has_bimodal_variant one UNIQUE-TIE-SHARPENING axis over (existential >= 1 → uniqueness == 1). Not a fresh substrate primitive on the index axis — the predicate emerges from one strict-equality test of the just-lifted Self::count_bimodal_variants scalar against 1, equivalently the Vec::len equality of the declaration-order intersection witness-collection Self::bimodal_variants against 1.

fn unique_extremal_variant(items: &[Self]) -> Option<Self>

The N-ARY ORDERING-AGNOSTIC “THE unique extremal variant” projection — Some(v) iff items has a UNIQUE extremal witness (Self::has_unique_extremal_variant holds) AND v is the sole variant achieving EITHER Self::max_variant_count OR Self::min_variant_count, else None. Computed as the just- lifted set-level extremal-union uniqueness bit Self::has_unique_extremal_variant guarding the declaration- order union first-witness Self::extremal_variant projection: when the guard holds the union witness is unambiguous and lifted verbatim; when the guard falsifies the projection collapses to None. The Option<Self>-RETURN UNIQUE-TIE SHARPENING corner OPENING the (set-level × Option<Self> × statistical-aggregate × direction-composition × unique-tie) column past the four unsharpened (declaration/lex × union/complement/intersection) direction- composition first-witness peers (Self::extremal_variant, Self::sorted_extremal_variant, Self::middle_band_variant, Self::sorted_middle_band_variant, Self::bimodal_variant, Self::sorted_bimodal_variant) one UNIQUE-TIE-SHARPENING axis over on the modal-aggregation matrix, AND peer to Self::unique_modal_variant one DIRECTION-COMPOSITION axis over (argmax first-witness-if-unique → union first-witness-if-unique) AND peer to Self::has_unique_extremal_variant one RETURN-SHAPE axis over (set-level × bool union uniqueness bit → set-level × Option<Self> union witness-when-unique). Not a fresh substrate primitive on the index axis — the projection emerges from a boolean conjunction of the just-lifted set-level extremal-union uniqueness bit with the just-lifted declaration-order union first-witness projection under an Option-collapse when the guard falsifies.

fn unique_middle_band_variant(items: &[Self]) -> Option<Self>

The N-ARY ORDERING-AGNOSTIC “THE unique middle-band variant” projection — Some(v) iff items has a UNIQUE strict-interior witness (Self::has_unique_middle_band_variant holds) AND v is the sole variant with occurrence-count STRICTLY BETWEEN Self::max_variant_count AND Self::min_variant_count, else None. Computed as the just-lifted set-level middle-band uniqueness bit Self::has_unique_middle_band_variant guarding the declaration-order strict-interior first-witness Self::middle_band_variant projection: when the guard holds the complement witness is unambiguous and lifted verbatim; when the guard falsifies the projection collapses to None. The Option<Self>-RETURN UNIQUE-TIE SHARPENING corner CLOSING the complement arm of the (set-level × Option<Self> × direction- composition × unique-tie) row past the just-opened UNION arm Self::unique_extremal_variant one COMBINATOR axis over on the modal-aggregation matrix AND peer to Self::has_unique_middle_band_variant one RETURN-SHAPE axis over (set-level × bool complement uniqueness bit → set-level × Option<Self> complement witness-when-unique) AND peer to Self::middle_band_variant one UNIQUE-TIE-SHARPENING axis over (unsharpened declaration-order strict-interior first-witness → uniqueness-gated declaration-order strict-interior first-witness). Not a fresh substrate primitive on the index axis — the projection emerges from a boolean conjunction of the just-lifted set-level middle-band uniqueness bit with the just-lifted declaration-order strict-interior first-witness projection under an Option-collapse when the guard falsifies.

fn unique_bimodal_variant(items: &[Self]) -> Option<Self>

The N-ARY ORDERING-AGNOSTIC “THE unique bimodal variant” projection — Some(v) iff items has a UNIQUE flat-diagonal witness (Self::has_unique_bimodal_variant holds) AND v is the sole variant with occurrence-count sitting SIMULTANEOUSLY at BOTH Self::max_variant_count AND Self::min_variant_count (the uniformity-collapse max == min fixpoint), else None. Computed as the just-lifted set-level bimodal uniqueness bit Self::has_unique_bimodal_variant guarding the declaration-order intersection first-witness Self::bimodal_variant projection: when the guard holds the intersection witness is unambiguous and lifted verbatim; when the guard falsifies the projection collapses to None. The Option<Self>-RETURN UNIQUE-TIE SHARPENING corner CLOSING the intersection arm of the (set-level × Option<Self> × direction-composition × unique-tie) row past the just-opened UNION arm Self::unique_extremal_variant AND the just-closed COMPLEMENT arm Self::unique_middle_band_variant one COMBINATOR axis over on the modal-aggregation matrix AND EXHAUSTIVELY CLOSING the (Option<Self> × direction-composition × combinator × unique-tie) 3-corner row at its FINAL THIRD tile past the union + complement arms AND peer to Self::has_unique_bimodal_variant one RETURN-SHAPE axis over (set-level × bool intersection uniqueness bit → set-level × Option<Self> intersection witness-when-unique) AND peer to Self::bimodal_variant one UNIQUE-TIE-SHARPENING axis over (unsharpened declaration-order intersection first-witness → uniqueness-gated declaration-order intersection first-witness). Not a fresh substrate primitive on the index axis — the projection emerges from a boolean conjunction of the just-lifted set-level bimodal uniqueness bit with the declaration-order intersection first-witness projection under an Option-collapse when the guard falsifies.

fn unique_extremal_variants(items: &[Self]) -> Vec<Self>

The N-ARY ORDERING-AGNOSTIC “the unique extremal witness as a singleton-or-empty Vec” projection — returns vec![v] iff items has a UNIQUE extremal witness (Self::has_unique_extremal_variant holds) AND v is the sole variant achieving EITHER Self::max_variant_count OR Self::min_variant_count, else vec![]. Computed as the just-lifted set-level extremal-union uniqueness bit Self::has_unique_extremal_variant guarding the declaration-order union witness-collection Self::extremal_variants: when the guard holds the collection is already a length-1 Vec by the guard’s own definition (count_extremal_variants == 1) and is lifted verbatim; when the guard falsifies the projection collapses to the EMPTY Vec through a zero-allocation ::std::vec::Vec::new() short-circuit. The Vec<Self>-RETURN UNIQUE-TIE SHARPENING corner OPENING the (set-level × Vec<Self> × statistical-aggregate × direction- composition × unique-tie) column past the six unsharpened (declaration/lex × union/complement/intersection) direction- composition witness-collection peers (Self::extremal_variants, Self::sorted_extremal_variants, Self::middle_band_variants, Self::sorted_middle_band_variants, Self::bimodal_variants, Self::sorted_bimodal_variants) one UNIQUE-TIE-SHARPENING axis over on the modal-aggregation matrix AND peer to Self::unique_extremal_variant (set-level × Option<Self> × union × unique-tie) one RETURN-SHAPE axis over (Option-return witness-when-unique → Vec-return singleton-or-empty-when-unique) AND peer to Self::has_unique_extremal_variant (set-level × bool × union × unique-tie) one RETURN-SHAPE axis over (bool uniqueness bit → Vec-return singleton-or-empty carrier of the same bit). Not a fresh substrate primitive on the index axis — the projection emerges from the boolean-guarded selection of the just- lifted declaration-order union witness-collection under the set- level extremal-union uniqueness bit, collapsing to the empty Vec through the guard-arm when the bit falsifies.

fn unique_middle_band_variants(items: &[Self]) -> Vec<Self>

The N-ARY ORDERING-AGNOSTIC “the unique strict-interior witness as a singleton-or-empty Vec” projection — returns vec![v] iff items has a UNIQUE strict-interior witness (Self::has_unique_middle_band_variant holds) AND v is the sole variant whose per-target multiplicity sits STRICTLY between Self::max_variant_count and Self::min_variant_count, else vec![]. Computed as the just- lifted set-level middle-band uniqueness bit Self::has_unique_middle_band_variant guarding the declaration- order complement witness-collection Self::middle_band_variants: when the guard holds the collection is already a length-1 Vec by the guard’s own definition (count_middle_band_variants == 1) and is lifted verbatim; when the guard falsifies the projection collapses to the EMPTY Vec through a zero-allocation ::std::vec::Vec::new() short-circuit. The Vec<Self>-RETURN UNIQUE-TIE SHARPENING corner CLOSING the complement arm of the (set-level × Vec<Self> × statistical-aggregate × direction- composition × combinator × unique-tie) row past the just-opened UNION arm Self::unique_extremal_variants one COMBINATOR axis over on the modal-aggregation matrix, peer to Self::unique_middle_band_variant (set-level × Option<Self> × complement × unique-tie) one RETURN-SHAPE axis over (Option-return witness-when-unique → Vec-return singleton-or-empty-when-unique) AND peer to Self::has_unique_middle_band_variant (set-level × bool × complement × unique-tie) one RETURN-SHAPE axis over (bool uniqueness bit → Vec-return singleton-or-empty carrier of the same bit). Not a fresh substrate primitive on the index axis — the projection emerges from the boolean-guarded selection of the just- lifted declaration-order complement witness-collection under the set-level middle-band uniqueness bit, collapsing to the empty Vec through the guard-arm when the bit falsifies.

fn unique_bimodal_variants(items: &[Self]) -> Vec<Self>

The N-ARY ORDERING-AGNOSTIC “the unique intersection-band witness as a singleton-or-empty Vec” projection — returns Self::bimodal_variants iff items has a UNIQUE intersection-band witness (Self::has_unique_bimodal_variant holds — equivalently the histogram is flat AND T::CARDINALITY == 1), else vec![]. Computed as the just-lifted set-level intersection-band uniqueness bit Self::has_unique_bimodal_variant guarding the declaration- order intersection witness-collection Self::bimodal_variants: when the guard holds the collection is already a length-1 Vec by the guard’s own definition (count_bimodal_variants == 1) and is lifted verbatim; when the guard falsifies the projection collapses to the EMPTY Vec through a zero-allocation ::std::vec::Vec::new() short-circuit. The Vec<Self>-RETURN UNIQUE-TIE SHARPENING corner CLOSING the intersection arm of the (set-level × Vec<Self> × statistical-aggregate × direction- composition × combinator × unique-tie) row past the just-opened UNION arm Self::unique_extremal_variants AND the just-closed COMPLEMENT arm Self::unique_middle_band_variants one COMBINATOR axis over on the modal-aggregation matrix AND EXHAUSTIVELY CLOSING the (Vec<Self> × direction-composition × combinator × unique-tie) 3-corner row at its FINAL THIRD tile, peer to Self::unique_bimodal_variant (set-level × Option<Self> × intersection × unique-tie) one RETURN-SHAPE axis over (Option- return witness-when-unique → Vec-return singleton-or-empty-when- unique) AND peer to Self::has_unique_bimodal_variant (set-level × bool × intersection × unique-tie) one RETURN-SHAPE axis over (bool uniqueness bit → Vec-return singleton-or-empty carrier of the same bit). Not a fresh substrate primitive on the index axis — the projection emerges from the boolean-guarded selection of the just-lifted declaration-order intersection witness-collection under the set-level intersection-band uniqueness bit, collapsing to the empty Vec through the guard-arm when the bit falsifies.

fn sorted_unique_extremal_variants(items: &[Self]) -> Vec<Self>

The N-ARY ORDERING-AGNOSTIC “unique extremal witnesses in LEX order, as a singleton-or-empty Vec” projection — returns Self::sorted_extremal_variants iff items has a UNIQUE extremum (Self::has_unique_extremal_variant holds), else vec![]. Computed as the just-lifted set-level extremal uniqueness bit Self::has_unique_extremal_variant guarding the LEX-ORDER union witness-collection Self::sorted_extremal_variants: when the guard holds the collection is already a length-1 Vec by the guard’s own definition (count_extremal_variants == 1) and is lifted verbatim; when the guard falsifies the projection collapses to the EMPTY Vec through a zero-allocation ::std::vec::Vec::new() short-circuit. The LEX-ORDER Vec<Self>-RETURN UNIQUE-TIE SHARPENING corner OPENING the LEX-ORDER (Vec<Self> × direction-composition × combinator × unique-tie) row past the just-closed declaration-order trio (Self::unique_extremal_variants, Self::unique_middle_band_variants, Self::unique_bimodal_variants) one ORDERING axis over on the modal-aggregation matrix, peer to Self::unique_extremal_variants one ORDERING axis over (declaration-order → lex-order union witness-collection-when-unique) AND peer to Self::sorted_extremal_variants one UNIQUE-TIE-SHARPENING axis over (unsharpened lex-order union witness-collection → uniqueness-gated lex-order union witness-collection) AND peer to Self::sorted_unique_extremal_variant one RETURN-SHAPE axis over (Option-return lex-first-witness-when-unique → Vec-return singleton-or-empty-when-unique). Not a fresh substrate primitive on the index axis — the projection emerges from the boolean-guarded selection of the just-lifted lex-order union witness-collection under the set-level extremal uniqueness bit, collapsing to the empty Vec through the guard-arm when the bit falsifies.

fn sorted_unique_middle_band_variants(items: &[Self]) -> Vec<Self>

The N-ARY ORDERING-AGNOSTIC “unique middle-band witnesses in LEX order, as a singleton-or-empty Vec” projection — returns Self::sorted_middle_band_variants iff items has a UNIQUE strict- interior variant (Self::has_unique_middle_band_variant holds), else vec![]. Computed as the just-lifted set-level middle-band uniqueness bit Self::has_unique_middle_band_variant guarding the LEX-ORDER complement witness-collection Self::sorted_middle_band_variants: when the guard holds the collection is already a length-1 Vec by the guard’s own definition (count_middle_band_variants == 1) and is lifted verbatim; when the guard falsifies the projection collapses to the EMPTY Vec through a zero-allocation ::std::vec::Vec::new() short-circuit. The LEX-ORDER Vec<Self>-RETURN COMPLEMENT UNIQUE-TIE SHARPENING corner CLOSING the complement arm of the LEX-ORDER (Vec<Self> × direction-composition × combinator × unique-tie) row past the just-opened union arm Self::sorted_unique_extremal_variants one COMBINATOR axis over on the modal-aggregation matrix, peer to Self::unique_middle_band_variants one ORDERING axis over (declaration-order → lex-order complement witness-collection-when- unique) AND peer to Self::sorted_middle_band_variants one UNIQUE- TIE-SHARPENING axis over (unsharpened lex-order complement witness- collection → uniqueness-gated lex-order complement witness-collection) AND peer to Self::sorted_unique_middle_band_variant one RETURN- SHAPE axis over (Option-return lex-first-witness-when-unique → Vec- return singleton-or-empty-when-unique). Not a fresh substrate primitive on the index axis — the projection emerges from the boolean-guarded selection of the just-lifted lex-order complement witness-collection under the set-level middle-band uniqueness bit, collapsing to the empty Vec through the guard-arm when the bit falsifies.

fn sorted_unique_bimodal_variants(items: &[Self]) -> Vec<Self>

The N-ARY ORDERING-AGNOSTIC “the unique intersection-band witness in LEX order, as a singleton-or-empty Vec” projection — returns Self::sorted_bimodal_variants iff items has a UNIQUE intersection- band witness (Self::has_unique_bimodal_variant holds — equivalently the histogram is flat AND T::CARDINALITY == 1), else vec![]. Computed as the just-lifted set-level intersection-band uniqueness bit Self::has_unique_bimodal_variant guarding the LEX-ORDER intersection witness-collection Self::sorted_bimodal_variants: when the guard holds the collection is already a length-1 Vec by the guard’s own definition (count_bimodal_variants == 1) and is lifted verbatim; when the guard falsifies the projection collapses to the EMPTY Vec through a zero-allocation ::std::vec::Vec::new() short-circuit. The LEX-ORDER Vec<Self>-RETURN INTERSECTION UNIQUE-TIE SHARPENING corner CLOSING the intersection arm of the LEX-ORDER (Vec<Self> × direction- composition × combinator × unique-tie) row past the just-opened UNION arm Self::sorted_unique_extremal_variants AND the just-closed COMPLEMENT arm Self::sorted_unique_middle_band_variants one COMBINATOR axis over on the modal-aggregation matrix AND EXHAUSTIVELY CLOSING the (set-level × Vec<Self> × direction-composition × combinator × ordering × unique-tie) 3×2 face at its FINAL SIXTH TILE, peer to Self::unique_bimodal_variants one ORDERING axis over (declaration-order → lex-order intersection witness-collection-when- unique) AND peer to Self::sorted_bimodal_variants one UNIQUE-TIE- SHARPENING axis over (unsharpened lex-order intersection witness- collection → uniqueness-gated lex-order intersection witness- collection) AND peer to Self::sorted_unique_bimodal_variant one RETURN-SHAPE axis over (Option-return lex-first-witness-when-unique → Vec-return singleton-or-empty-when-unique). Not a fresh substrate primitive on the index axis — the projection emerges from the boolean- guarded selection of the just-lifted lex-order intersection witness- collection under the set-level intersection-band uniqueness bit, collapsing to the empty Vec through the guard-arm when the bit falsifies.

fn is_unique_extremal_variant_of(target: Self, items: &[Self]) -> bool

The N-ARY ORDERING-AGNOSTIC “target is THE UNIQUE extremal variant” per-target predicate — true iff target is an extremal variant of items (its per-target multiplicity sits on the union of the argmax and argmin bands via Self::is_extremal_variant_of) AND items has a unique extremum (Self::count_extremal_variants == 1), computed as the conjunction of the per-target union membership predicate Self::is_extremal_variant_of with the set-level extremal-uniqueness predicate Self::has_unique_extremal_variant. The BOOL-RETURN PER-TARGET UNION UNIQUE-TIE SHARPENING corner OPENING the (per-target × bool × statistical-aggregate × direction- composition × union × unique-tie) column past the direction-anchored (is_unique_modal_variant_of, is_unique_antimodal_variant_of) pair one DIRECTION-COMPOSITION axis over on the modal-aggregation matrix AND peer to Self::has_unique_extremal_variant (set-level × bool × union × unique-tie) one ARITY axis over AND peer to Self::is_extremal_variant_of (per-target × bool × union) one UNIQUE-TIE-SHARPENING axis over AND peer to Self::unique_extremal_variant (set-level × Option<Self> × union × unique-tie) one ARITY axis over. Not a fresh substrate primitive on the index axis — the predicate emerges from the conjunction of the just-lifted per-target union membership predicate with the just-lifted set-level extremal-uniqueness scalar, equivalently the strict-equality test of the just-lifted first- witness Self::unique_extremal_variant projection against Some(target).

fn is_unique_middle_band_variant_of(target: Self, items: &[Self]) -> bool

The N-ARY ORDERING-AGNOSTIC PER-TARGET “is target the SOLE strictly-interior variant?” predicate — true iff target sits STRICTLY BETWEEN the max and min counts of items AND exactly ONE variant of Self::ALL sits on that strict- interior band, computed as the just-lifted per-target complement membership Self::is_middle_band_variant_of projection conjoined with the just-lifted set-level complement uniqueness bit Self::has_unique_middle_band_variant via &&. The (per-target × bool × direction-composition × complement × unique-tie) corner CLOSING the complement arm of the (per- target × bool × direction-composition × combinator × unique- tie) 3-corner row past the just-opened union arm Self::is_unique_extremal_variant_of one COMBINATOR axis over.

fn is_unique_bimodal_variant_of(target: Self, items: &[Self]) -> bool

The N-ARY ORDERING-AGNOSTIC PER-TARGET “is target the SOLE flat-diagonal variant?” predicate — true iff target sits on BOTH the argmax AND the argmin bands of items simultaneously AND exactly ONE variant of Self::ALL sits on that intersection band, computed as the just-lifted per-target intersection membership Self::is_bimodal_variant_of projection conjoined with the just-lifted set-level intersection uniqueness bit Self::has_unique_bimodal_variant via &&. The (per-target × bool × direction-composition × intersection × unique-tie) corner CLOSING the intersection arm of the (per-target × bool × direction-composition × combinator × unique-tie) 3-corner row past the just-opened union arm Self::is_unique_extremal_variant_of AND the just-closed complement arm Self::is_unique_middle_band_variant_of one COMBINATOR axis over AND EXHAUSTIVELY CLOSING the (per-target × bool × direction-composition × combinator × unique-tie) 3-corner row at its FINAL THIRD tile.

fn is_repeating_any(items: &[Self]) -> bool

The N-ARY ORDERING-AGNOSTIC “any variant repeating?” predicate — true iff AT LEAST ONE variant of Self::ALL appears TWO OR MORE times in items, computed as the just-lifted usize-return Self::max_variant_count projection MEETING-OR-EXCEEDING the scalar threshold 2. The BOOL-RETURN opener on the (set-level × bool × multiplicity-band >= 2) corner peer to the (set-level × bool × multiplicity-band == 0) Self::is_missing_any corner one MULTIPLICITY-BAND axis over, AND the direct SET-LEVEL EXISTENTIAL LIFT of the (per-target × bool × multiplicity-band >= 2) Self::is_repeated_occurrence_of corner one ARITY axis over on the (arity × mult-band) face of the equivalence-partition surface. Not a fresh substrate primitive on the index axis — the predicate emerges from one comparison of the just-lifted Self::max_variant_count modal-count aggregate against 2, equivalently the disjunction over Self::ALL of the per-target Self::is_repeated_occurrence_of predicate.

fn is_unique_any(items: &[Self]) -> bool

The N-ARY ORDERING-AGNOSTIC “any variant unique?” predicate — true iff AT LEAST ONE variant of Self::ALL appears EXACTLY ONCE in items, computed as the disjunction over Self::ALL of the per-target Self::is_unique_occurrence_of predicate. The BOOL-RETURN closer on the (set-level × bool × multiplicity- band) 3-corner existential-lift face at its final == 1 corner peer to the (set-level × bool × multiplicity-band == 0) Self::is_missing_any corner and the (set-level × bool × multiplicity-band >= 2) Self::is_repeating_any corner one MULTIPLICITY-BAND axis over, AND the direct SET-LEVEL EXISTENTIAL LIFT of the (per-target × bool × multiplicity-band == 1) Self::is_unique_occurrence_of corner one ARITY axis over on the (arity × mult-band) face of the equivalence- partition surface. Not a fresh substrate primitive on the index axis — the predicate emerges from one existential disjunction over Self::ALL of the per-target multiplicity- == 1 predicate, equivalently the histogram vector’s containment of the scalar 1.

fn count_unique_variants(items: &[Self]) -> usize

The N-ARY ORDERING-AGNOSTIC “count of unique-multiplicity variants” projection — the usize count of variants of Self::ALL whose per-target multiplicity in items equals EXACTLY 1, computed as the .count() reduction of Self::ALL filtered through the per-target Self::is_unique_occurrence_of predicate. The SET-LEVEL USIZE-RETURN closer on the (set-level × usize × multiplicity- band) 3-corner face at the middle band peer to the (set-level × usize × multiplicity-band == 0) Self::count_missing corner one MULTIPLICITY-BAND axis over, AND the direct USIZE-RETURN SHARPENING of the (set-level × bool × multiplicity-band == 1) Self::is_unique_any corner one return-shape axis over — while Self::is_unique_any reports “IS THERE at least one variant occurring exactly once?” (a set-level bool), this projection reports “HOW MANY variants occur exactly once?” (a set-level usize that is a strict refinement of the bool). Not a fresh substrate primitive on the index axis — the count emerges from one composition of Self::ALL filtered through the per-target Self::is_unique_occurrence_of uniqueness primitive.

fn count_repeating_variants(items: &[Self]) -> usize

The N-ARY ORDERING-AGNOSTIC “how many variants occur two or more times?” cardinality-count projection — the usize SET-LEVEL count of variants of Self::ALL whose per-target multiplicity in items is STRICTLY AT LEAST 2, computed as the filter-count reduction over Self::ALL of the per-target Self::is_repeated_occurrence_of predicate. The USIZE-RETURN closer on the (set-level × usize × multiplicity-band) 3-corner cardinality-count face at its final >= 2 strict-repeat corner peer to the (set-level × usize × multiplicity-band == 0) Self::count_missing corner and the (set-level × usize × multiplicity-band == 1) Self::count_unique_variants corner one MULTIPLICITY-BAND axis over, AND the direct SET- LEVEL EXISTENTIAL-COUNT SHARPENING of the (set-level × bool × multiplicity-band >= 2) Self::is_repeating_any predicate one return-shape axis over (bool-return → usize-return via cardinality sharpening) on the (arity × mult-band × return- shape) face of the equivalence-partition surface. Not a fresh substrate primitive on the index axis — the count emerges from one filter-count reduction over Self::ALL of the per-target multiplicity->= 2 predicate, equivalently the count of per- slot histogram bars strictly at least 2.

fn has_unique_repeating_variant(items: &[Self]) -> bool

The N-ARY ORDERING-AGNOSTIC “does the STRICT-REPEAT band fall on a UNIQUE variant?” set-level predicate — true iff EXACTLY ONE variant of Self::ALL carries an occurrence-count STRICTLY AT LEAST 2 in items, computed as the strict-equality test of the just-lifted Self::count_repeating_variants cardinality-count aggregate against the scalar threshold 1. The BOOL-RETURN UNIQUE-TIE SHARPENING corner OPENING the (set-level × bool × equivalence-partition × multiplicity-band × unique-tie) row on the EQUIVALENCE-PARTITION surface at its (mult >= 2) band, peer to Self::count_repeating_variants one RETURN-SHAPE axis over (set-level × usize cardinality → set-level × bool uniqueness test against 1), peer to Self::is_repeating_any one UNIQUE- TIE-SHARPENING axis over (existential >= 1 → uniqueness == 1) AND peer to Self::has_unique_extremal_variant + Self::has_unique_middle_band_variant + Self::has_unique_bimodal_variant one SURFACE axis over — those three land the same unique-tie sharpening on the modal- AGGREGATION surface (direction-composition × combinator); THIS projection lands it on the equivalence-PARTITION surface (multiplicity-band). Not a fresh substrate primitive on the index axis — the predicate emerges from one strict-equality test of the just-lifted Self::count_repeating_variants scalar against 1, equivalently the Vec::len equality of the declaration-order strict-repeat witness-collection Self::repeating_variants against 1.

fn unique_repeating_variant(items: &[Self]) -> Option<Self>

The N-ARY ORDERING-AGNOSTIC “THE unique strict-repeat variant” projection — Some(v) iff items has a UNIQUE strict-repeat witness (Self::has_unique_repeating_variant holds) AND v is the sole variant whose per-target multiplicity in items sits STRICTLY AT LEAST 2 (equivalently, the sole variant on Self::ALL satisfying Self::is_repeated_occurrence_of at this slice), else None. Computed as the just-lifted set-level strict-repeat uniqueness bit Self::has_unique_repeating_variant guarding a declaration-order first-witness sweep of Self::ALL through the substrate’s per-target strict-repeat primitive Self::is_repeated_occurrence_of: when the guard holds the sweep hits EXACTLY ONE variant and the sole witness lifts through verbatim; when the guard falsifies the projection collapses to None. The Option<Self>-RETURN UNIQUE-TIE SHARPENING corner OPENING the (set-level × Option<Self> × equivalence-partition × multiplicity-band >= 2 × unique-tie) column past the just- lifted Self::has_unique_repeating_variant one RETURN-SHAPE axis over (set-level × bool strict-repeat uniqueness bit → set-level × Option<Self> strict-repeat witness-when-unique) AND peer to Self::unique_extremal_variant + Self::unique_middle_band_variant + Self::unique_bimodal_variant one SURFACE axis over — those three land the same Option<Self> uniqueness-guarded witness on the MODAL-AGGREGATION surface (direction-composition × combinator); THIS projection lands it on the EQUIVALENCE-PARTITION surface (multiplicity-band). Not a fresh substrate primitive on the index axis — the projection emerges from the just-lifted set-level strict-repeat uniqueness bit guarding a first-witness sweep of Self::ALL through the substrate’s per-target strict-repeat primitive under an Option-collapse when the guard falsifies.

fn is_unique_repeating_variant_of(target: Self, items: &[Self]) -> bool

The N-ARY ORDERING-AGNOSTIC PER-TARGET “is target the SOLE strictly-repeating variant?” predicate — true iff target occurs TWO OR MORE times in items AND exactly ONE variant of Self::ALL sits on that strict-repeat band, computed as the substrate’s per-target strict-repeat membership Self::is_repeated_occurrence_of projection conjoined with the just-lifted set-level strict-repeat uniqueness bit Self::has_unique_repeating_variant via &&. The (per- target × bool × equivalence-partition × multiplicity-band >= 2 × unique-tie sharpening) corner OPENING the equivalence- partition arm of the (per-target × bool × unique-tie) column peer to Self::is_unique_extremal_variant_of + Self::is_unique_middle_band_variant_of + Self::is_unique_bimodal_variant_of one SURFACE axis over — those three land the same bool uniqueness-guarded predicate on the MODAL-AGGREGATION surface (direction-composition × combinator); THIS projection lands it on the EQUIVALENCE- PARTITION surface (multiplicity-band). AND peer to Self::has_unique_repeating_variant one ARITY axis over, AND peer to Self::unique_repeating_variant one RETURN- SHAPE axis over. Not a fresh substrate primitive on the index axis — the predicate emerges from the boolean conjunction of the substrate’s per-target strict-repeat primitive with the just-lifted set-level strict-repeat uniqueness bit.

fn has_unique_missing_variant(items: &[Self]) -> bool

The N-ARY ORDERING-AGNOSTIC “does the (mult == 0) MISS-band fall on a UNIQUE variant?” set-level predicate — true iff EXACTLY ONE variant of Self::ALL is ABSENT from items (i.e., items hits every variant except one), computed as the strict-equality test of Self::count_missing against the scalar threshold 1. The BOOL-RETURN UNIQUE-TIE SHARPENING corner CLOSING the miss-band arm of the (set- level × bool × equivalence-partition × multiplicity-band × unique-tie) row on the EQUIVALENCE-PARTITION surface at its (mult == 0) band, peer to Self::has_unique_repeating_variant (mult >= 2) one MULTIPLICITY-BAND axis over — the two together bracket the unique-tie sharpening at BOTH extremal bands of the mult-band trichotomy; peer to Self::count_missing one RETURN-SHAPE axis over (set- level × usize miss-cardinality → set-level × bool miss- uniqueness test against 1); peer to Self::is_missing_any one UNIQUE-TIE-SHARPENING axis over (existential >= 1 → uniqueness == 1). Not a fresh substrate primitive on the index axis — the predicate emerges from one strict-equality test of the substrate’s Self::count_missing scalar against 1, equivalently the Vec::len equality of the declaration-order miss witness-collection Self::missing_variants against 1.

fn has_unique_unique_variant(items: &[Self]) -> bool

The N-ARY ORDERING-AGNOSTIC “does the (mult == 1) UNIQUE-band fall on a UNIQUE variant?” set-level predicate — true iff EXACTLY ONE variant of Self::ALL occurs at multiplicity EXACTLY 1 in items (i.e., items has EXACTLY ONE singleton-multiplicity witness on its per-variant histogram), computed as the strict-equality test of Self::count_unique_variants against the scalar threshold 1. The BOOL-RETURN UNIQUE-TIE SHARPENING corner EXHAUSTIVELY CLOSING the middle-band arm of the (set-level × bool × equivalence-partition × multiplicity-band × unique- tie) row on the EQUIVALENCE-PARTITION surface at its (mult == 1) band — the row’s FINAL THIRD tile past the just-lifted (mult == 0) Self::has_unique_missing_variant miss-band arm and the (mult >= 2) Self::has_unique_repeating_variant strict-repeat arm one MULTIPLICITY-BAND axis over. The three together bracket the unique-tie sharpening across ALL THREE bands of the mult- band trichotomy (== 0, == 1, >= 2), exhaustively closing the (set-level × bool × equivalence-partition × mult-band × unique-tie) 3-corner row on the equivalence- partition surface — the mirror closure of the (set-level × usize × equivalence-partition × mult-band) 3-corner cardinality-count row (Self::count_missing, Self::count_unique_variants, Self::count_repeating_variants) one RETURN-SHAPE axis over on the equivalence-partition surface, AND the mirror closure of the (set-level × bool × equivalence-partition × mult-band × existential) 3-corner existential-lift row (Self::is_missing_any, Self::is_unique_any, Self::is_repeating_any) one UNIQUE-TIE-SHARPENING axis over. Peer to Self::count_unique_variants one RETURN- SHAPE axis over (set-level × usize unique-cardinality → set-level × bool unique-uniqueness test against 1); peer to Self::is_unique_any one UNIQUE-TIE-SHARPENING axis over (existential >= 1 → uniqueness == 1). Not a fresh substrate primitive on the index axis — the predicate emerges from one strict-equality test of the substrate’s Self::count_unique_variants scalar against 1, equivalently the count of per-variant histogram bars strictly equal to 1 collapsed to a == 1 bit.

fn unique_unique_variant(items: &[Self]) -> Option<Self>

The N-ARY ORDERING-AGNOSTIC “THE unique unique-band variant” projection — Some(v) iff items has a UNIQUE singleton- multiplicity witness (Self::has_unique_unique_variant holds) AND v is the sole variant whose per-target multiplicity in items sits EXACTLY at 1 (equivalently, the sole variant on Self::ALL satisfying Self::is_unique_occurrence_of at this slice), else None. Computed as the just-lifted set-level unique-band uniqueness bit Self::has_unique_unique_variant guarding a declaration-order first-witness sweep of Self::ALL through the substrate’s per-target singleton-multiplicity primitive Self::is_unique_occurrence_of: when the guard holds the sweep hits EXACTLY ONE variant and the sole witness lifts through verbatim; when the guard falsifies the projection collapses to None. The Option<Self>-RETURN UNIQUE-TIE SHARPENING corner EXHAUSTIVELY CLOSING the middle-band arm of the (set-level × Option<Self> × equivalence-partition × multiplicity-band × unique-tie) row on the EQUIVALENCE-PARTITION surface at its (mult == 1) band — the row’s FINAL THIRD tile past the just-lifted (mult >= 2) Self::unique_repeating_variant strict-repeat arm one MULTIPLICITY-BAND axis over. Peer to Self::has_unique_unique_variant one RETURN-SHAPE axis over (set-level × bool unique-band uniqueness bit → set-level × Option<Self> unique-band witness-when-unique); peer to Self::unique_repeating_variant one MULTIPLICITY-BAND axis over (mult >= 2 Option<Self> strict-repeat witness → mult == 1 Option<Self> unique-band witness). Not a fresh substrate primitive on the index axis — the projection emerges from the just-lifted set-level unique-band uniqueness bit guarding a first-witness sweep of Self::ALL through the substrate’s per-target singleton-multiplicity primitive under an Option-collapse when the guard falsifies.

fn unique_missing_variant(items: &[Self]) -> Option<Self>

The N-ARY ORDERING-AGNOSTIC “THE unique missing variant” projection — Some(v) iff items has a UNIQUE miss-band witness (Self::has_unique_missing_variant holds) AND v is the sole variant of Self::ALL whose per-target multiplicity sits at == 0, else None. Computed as the just-lifted set-level miss-band uniqueness bit Self::has_unique_missing_variant guarding a declaration-order first-witness sweep of Self::ALL keyed on !<Self as ClosedSet>::occurs_in: when the guard holds the sweep hits the SOLE missing variant unambiguously; when the guard falsifies the projection collapses to None. The Option<Self>-RETURN UNIQUE-TIE SHARPENING corner EXHAUSTIVELY CLOSING the miss-band arm of the (set-level × Option<Self> × equivalence-partition × multiplicity-band × unique-tie) row on the EQUIVALENCE-PARTITION surface at its (mult == 0) band — the FINAL THIRD tile past the just-lifted (mult >= 2) peer Self::unique_repeating_variant and the (mult == 1) peer Self::unique_unique_variant one MULTIPLICITY-BAND axis over. Together the three EXHAUSTIVELY CLOSE the (set-level × Option<Self> × equivalence-partition × mult-band × unique-tie) trichotomy row on the equivalence-partition surface — peer to Self::has_unique_missing_variant one RETURN-SHAPE axis over (set-level × bool miss-band uniqueness bit → set-level × Option<Self> miss-band witness-when-unique) AND peer to Self::unique_extremal_variant + Self::unique_middle_band_variant + Self::unique_bimodal_variant one SURFACE axis over on the modal-aggregation matrix. Not a fresh substrate primitive on the index axis — the projection emerges from a boolean conjunction of the just-lifted set-level miss-band uniqueness bit with a declaration-order first-witness Iterator::find sweep under an Option-collapse when the guard falsifies.

fn sorted_unique_missing_variant(items: &[Self]) -> Option<Self>

The N-ARY ORDERING-AGNOSTIC “THE unique missing variant, lex- first” projection — Some(v) iff items has a UNIQUE miss-band witness (Self::has_unique_missing_variant holds) AND v is the sole variant of Self::sorted_variants whose per-target multiplicity sits at == 0, else None. Computed as the just- lifted set-level miss-band uniqueness bit Self::has_unique_missing_variant guarding a LEX-ORDER first- witness sweep of Self::sorted_variants keyed on !<Self as ClosedSet>::occurs_in. The LEX-ORDER Option<Self>- RETURN UNIQUE-TIE SHARPENING corner OPENING the (set-level × Option<Self> × ordering × equivalence-partition × multiplicity-band × unique-tie) row on the EQUIVALENCE-PARTITION surface at its (mult == 0) miss-band arm — the lex-ordering peer of the just-lifted declaration-order Self::unique_missing_variant one ORDERING axis over, peer to Self::sorted_missing_variants one UNIQUE-TIE-SHARPENING axis over (existential >= 1 Vec of misses → uniqueness == 1 Option<Self> collapse), AND peer to Self::sorted_extremal_variant + Self::sorted_middle_band_variant + Self::sorted_bimodal_variant one SURFACE axis over on the modal-aggregation matrix. Not a fresh substrate primitive on the index axis — the projection emerges from a boolean conjunction of the just-lifted set-level miss-band uniqueness bit with a lex-order first-witness Iterator::find sweep of Self::sorted_variants under an Option-collapse when the guard falsifies.

fn sorted_unique_repeating_variant(items: &[Self]) -> Option<Self>

The N-ARY ORDERING-AGNOSTIC “THE unique strictly-repeating variant, lex-first” projection — Some(v) iff items has a UNIQUE strict- repeat witness (Self::has_unique_repeating_variant holds) AND v is the sole variant of Self::sorted_variants whose per- target multiplicity sits at >= 2, else None. Computed as the just-lifted set-level strict-repeat uniqueness bit Self::has_unique_repeating_variant guarding a LEX-ORDER first- witness sweep of Self::sorted_variants keyed on Self::is_repeated_occurrence_of. The LEX-ORDER Option<Self>- RETURN UNIQUE-TIE SHARPENING corner OPENING the (set-level × Option<Self> × sorted × equivalence-partition × multiplicity-band × unique-tie) row on the EQUIVALENCE-PARTITION surface at its (mult >= 2) strict-repeat arm — the lex-ordering peer of the just-closed declaration-order Self::unique_repeating_variant one ORDERING axis over, peer to Self::sorted_repeating_variants one UNIQUE-TIE-SHARPENING axis over (existential >= 1 Vec of strict-repeaters → uniqueness == 1 Option<Self> collapse), AND peer to Self::sorted_unique_missing_variant one MULTIPLICITY-BAND axis over on the equivalence-partition surface (the two together bracket the LEX-ORDER Option<Self> unique-tie sharpening at BOTH EXTREMAL bands of the mult-band trichotomy — the mult == 1 middle arm sorted_unique_unique_variant remains the last tile). Not a fresh substrate primitive on the index axis — the projection emerges from a boolean conjunction of the set-level strict-repeat uniqueness bit with a lex-order first-witness Iterator::find sweep of Self::sorted_variants under an Option-collapse when the guard falsifies.

fn sorted_unique_unique_variant(items: &[Self]) -> Option<Self>

The N-ARY ORDERING-AGNOSTIC “THE unique unique-band variant, lex-first” projection — Some(v) iff items has a UNIQUE singleton-multiplicity witness (Self::has_unique_unique_variant holds) AND v is the sole variant of Self::sorted_variants whose per-target multiplicity sits EXACTLY at 1, else None. Computed as the just-lifted set-level unique-band uniqueness bit Self::has_unique_unique_variant guarding a LEX-ORDER first- witness sweep of Self::sorted_variants keyed on the substrate’s per-target singleton-multiplicity primitive Self::is_unique_occurrence_of. The LEX-ORDER Option<Self>- RETURN UNIQUE-TIE SHARPENING corner EXHAUSTIVELY CLOSING the middle-band arm of the (set-level × Option<Self> × sorted × equivalence-partition × multiplicity-band × unique-tie) row on the EQUIVALENCE-PARTITION surface at its (mult == 1) band — the FINAL THIRD tile past the just-lifted (mult >= 2) Self::sorted_unique_repeating_variant strict-repeat arm AND the just-lifted (mult == 0) Self::sorted_unique_missing_variant miss-band arm one MULTIPLICITY-BAND axis over. Together the three EXHAUSTIVELY CLOSE the (set-level × Option<Self> × sorted × equivalence-partition × mult-band × unique-tie) trichotomy row on the LEX-ORDER equivalence-partition surface. Peer to Self::unique_unique_variant one ORDERING axis over (the declaration-order sibling this LEX peer is provably identical to), AND peer to Self::has_unique_unique_variant one RETURN-SHAPE axis over. Not a fresh substrate primitive on the index axis — the projection emerges from a boolean-guarded lex-order first-witness Iterator::find sweep of Self::sorted_variants under an Option-collapse when the guard falsifies.

fn is_unique_missing_variant_of(target: Self, items: &[Self]) -> bool

The N-ARY ORDERING-AGNOSTIC PER-TARGET “is target the SOLE absent variant?” predicate — true iff target does NOT occur in items AND exactly ONE variant of Self::ALL is missing from items, computed as the negation of the substrate’s per-target membership predicate Self::occurs_in conjoined with the just-lifted set-level miss-band uniqueness bit Self::has_unique_missing_variant via &&. The (per-target × bool × equivalence-partition × multiplicity-band == 0 × unique-tie sharpening) corner OPENING the miss-band arm of the (per-target × bool × equivalence-partition × mult-band × unique-tie) column past the just-opened (mult >= 2) Self::is_unique_repeating_variant_of strict-repeat arm one MULTIPLICITY-BAND axis over on the EQUIVALENCE-PARTITION surface — the two together bracket the per-target unique-tie sharpening at BOTH EXTREMAL bands of the mult-band trichotomy. Peer to Self::has_unique_missing_variant one ARITY axis over (set-level bool miss-band uniqueness bit → per-target bool miss-band membership-if-unique test); peer to Self::unique_missing_variant one RETURN-SHAPE axis over (set-level Option<Self> miss-band witness-when-unique → per-target bool miss-band membership-when-unique). Not a fresh substrate primitive on the index axis — the predicate emerges from the boolean conjunction of the negation of the substrate’s per-target membership primitive with the just- lifted set-level miss-band uniqueness bit.

fn is_unique_unique_variant_of(target: Self, items: &[Self]) -> bool

The N-ARY ORDERING-AGNOSTIC PER-TARGET “is target the SOLE singleton-multiplicity variant?” predicate — true iff target occurs EXACTLY ONCE in items AND exactly ONE variant of Self::ALL sits on that singleton-multiplicity band, computed as the substrate’s per-target singleton-multiplicity Self::is_unique_occurrence_of projection conjoined with the just-lifted set-level unique-band uniqueness bit Self::has_unique_unique_variant via &&. The (per-target × bool × equivalence-partition × multiplicity-band == 1 × unique-tie sharpening) corner EXHAUSTIVELY CLOSING the middle- band arm of the (per-target × bool × equivalence-partition × mult-band × unique-tie) 3-corner row on the EQUIVALENCE- PARTITION surface at its FINAL third tile past the (mult >= 2) Self::is_unique_repeating_variant_of strict-repeat arm AND the (mult == 0) Self::is_unique_missing_variant_of miss- band arm one MULTIPLICITY-BAND axis over — the three together EXHAUSTIVELY CLOSE the per-target unique-tie sharpening across the mult-band trichotomy, mirroring the same exhaustive closure at the set-level bool ( Self::has_unique_repeating_variant + Self::has_unique_missing_variant + Self::has_unique_unique_variant) row and set-level Option<Self> (Self::unique_repeating_variant + Self::unique_missing_variant + Self::unique_unique_variant) row. Peer to Self::has_unique_unique_variant one ARITY axis over AND peer to Self::unique_unique_variant one RETURN-SHAPE axis over — the (bool set-level, Option<Self> set-level, bool per- target) 3-corner mini-face on the middle-band arm of the equivalence-partition surface now closes at THIS third corner, mirroring the same 3-corner closure at the strict-repeat arm (Self::has_unique_repeating_variant, Self::unique_repeating_variant, Self::is_unique_repeating_variant_of) AND at the miss-band arm (Self::has_unique_missing_variant, Self::unique_missing_variant, Self::is_unique_missing_variant_of) one MULTIPLICITY-BAND axis over. Not a fresh substrate primitive on the index axis — the predicate emerges from the boolean conjunction of the substrate’s per-target singleton-multiplicity primitive with the just-lifted set-level unique-band uniqueness bit.

fn present_variants(items: &[Self]) -> Vec<Self>

The N-ARY ORDERING-AGNOSTIC “present variants” projection — the Vec<Self> DECLARATION-ORDER hit-set of Self::ALL, keeping every variant that OCCURS at least once in items and dropping every variant that does NOT. The VEC-RETURN PRESENT-ARM opener on the equivalence-partition surface, positioned as the concrete WITNESS behind the just-lifted bool-return Self::is_covering predicate (which reports whether the hit-set reaches full cardinality) and the usize-return Self::count_distinct projection (which reports the hit-set’s cardinality alone). Sibling posture to Self::missing_variants one column of the (partition-arm) axis over: this projection materializes the PRESENT arm as a Vec<Self> witness; Self::missing_variants materializes the ABSENT arm as a Vec<Self> witness. The (present, absent) × (bool, usize, Vec) 2×3 = 6-corner partition-arm × return-shape face on the equivalence- partition surface now opens the Vec-return column at BOTH partition arms.

fn missing_variants(items: &[Self]) -> Vec<Self>

The N-ARY ORDERING-AGNOSTIC “missing variants” projection — the Vec<Self> DECLARATION-ORDER miss-set of Self::ALL, keeping every variant that does NOT occur in items and dropping every variant that DOES. The VEC-RETURN ABSENT-ARM closer on the (present, absent) partition-arm axis over the Vec-return column of the equivalence-partition surface, positioned as the direct DE MORGAN dual of Self::present_variants and as the concrete WITNESS behind the just-lifted bool-return Self::is_missing_any predicate (which reports whether the miss-set is non-empty) and the usize-return Self::count_missing projection (which reports the miss-set’s cardinality alone).

fn repeating_variants(items: &[Self]) -> Vec<Self>

The N-ARY ORDERING-AGNOSTIC “repeating variants” projection — the Vec<Self> DECLARATION-ORDER strict-repeat set of Self::ALL, keeping every variant whose per-target multiplicity in items is >= 2 and dropping every variant whose multiplicity is <= 1. The VEC-RETURN STRICT-REPEAT corner OPENING the (Vec<Self>, set-level, multiplicity- band >= 2) column past the (bool, set-level, multiplicity-band >= 2) Self::is_repeating_any existential corner AND the (usize, set-level, multiplicity- band >= 2) Self::count_repeating_variants cardinality corner on the equivalence-partition surface, positioned as the concrete WITNESS behind those two peer projections (which report whether the strict-repeat set is non-empty and its cardinality alone, respectively).

fn sorted_present_variants(items: &[Self]) -> Vec<Self>

The N-ARY ORDERING-AGNOSTIC “present variants” projection — the Vec<Self> LEX-ORDER hit-set of Self::sorted_variants, keeping every variant that DOES occur in items and dropping every variant that doesn’t. The LEX-ORDER peer of Self::present_variants on the (declaration, lex) ordering axis of the Vec-return column of the equivalence-partition surface — opens the lex arm past the declaration arm the prior pair closed.

fn sorted_missing_variants(items: &[Self]) -> Vec<Self>

The N-ARY ORDERING-AGNOSTIC “missing variants” projection — the Vec<Self> LEX-ORDER miss-set of Self::sorted_variants, keeping every variant that does NOT occur in items and dropping every variant that DOES. The LEX-ORDER peer of Self::missing_variants on the (declaration, lex) ordering axis of the Vec-return column of the equivalence-partition surface — closes the lex arm past the declaration arm the sibling Self::sorted_present_variants opened.

fn sorted_repeating_variants(items: &[Self]) -> Vec<Self>

The N-ARY ORDERING-AGNOSTIC “repeating variants” projection — the Vec<Self> LEX-ORDER strict-repeat set of Self::sorted_variants, keeping every variant whose per- target multiplicity in items is >= 2 and dropping every variant whose multiplicity is <= 1. The LEX-ORDER peer of Self::repeating_variants on the (declaration, lex) ordering axis of the Vec<Self>-return strict-repeat-band column of the equivalence-partition surface — CLOSES the lex arm past the declaration arm the sibling Self::repeating_variants opened, and CLOSES the (partition- arm × ordering) 3×2 = 6-corner Vec<Self>-return face at its SIXTH (strict-repeat, lex) corner peer to Self::sorted_present_variants (present × lex) and Self::sorted_missing_variants (absent × lex) one PARTITION- ARM axis over on the same lex column.

fn unique_variants(items: &[Self]) -> Vec<Self>

The N-ARY ORDERING-AGNOSTIC “unique variants” projection — the Vec<Self> DECLARATION-ORDER strict-uniqueness set of Self::ALL, keeping every variant whose per-target multiplicity in items is EXACTLY 1 and dropping every variant whose multiplicity is 0 or >= 2. The VEC-RETURN STRICT-UNIQUENESS corner OPENING the (Vec<Self>, set-level, multiplicity-band == 1) column past the (bool, set-level, multiplicity-band == 1) Self::is_unique_any existential corner AND the (usize, set-level, multiplicity-band == 1) Self::count_unique_variants cardinality corner on the equivalence-partition surface, positioned as the concrete WITNESS behind those two peer projections (which report whether the strict-uniqueness set is non-empty and its cardinality alone, respectively).

fn sorted_unique_variants(items: &[Self]) -> Vec<Self>

The N-ARY ORDERING-AGNOSTIC “unique variants” projection — the Vec<Self> LEX-ORDER strict-uniqueness set of Self::sorted_variants, keeping every variant whose per- target multiplicity in items is EXACTLY 1 and dropping every variant whose multiplicity is 0 or >= 2. The LEX- ORDER peer of Self::unique_variants on the (declaration, lex) ordering axis of the Vec-return column of the equivalence-partition surface — closes the lex arm past the declaration arm the prior projection opens.

fn unique_missing_variants(items: &[Self]) -> Vec<Self>

The N-ARY ORDERING-AGNOSTIC “the unique miss-band witness as a singleton-or-empty Vec” projection — returns Self::missing_variants iff items has a UNIQUE miss-band witness (Self::has_unique_missing_variant holds) AND is the sole variant whose per-target multiplicity sits at == 0, else vec![]. Computed as the just-lifted set-level miss-band uniqueness bit Self::has_unique_missing_variant guarding the declaration-order miss-set witness-collection Self::missing_variants: when the guard holds the collection is already a length-1 Vec by the guard’s own definition (count_missing == 1) and is lifted verbatim; when the guard falsifies the projection collapses to the EMPTY Vec through a zero-allocation ::std::vec::Vec::new() short-circuit. The Vec<Self>-RETURN UNIQUE-TIE SHARPENING corner OPENING the (set-level × Vec<Self> × equivalence-partition × multiplicity-band × unique-tie) column past the eight unsharpened (declaration/lex × miss/repeat/unique/present) equivalence- partition witness-collection peers (Self::missing_variants, Self::sorted_missing_variants, Self::repeating_variants, Self::sorted_repeating_variants, Self::unique_variants, Self::sorted_unique_variants, Self::present_variants, Self::sorted_present_variants) one UNIQUE-TIE-SHARPENING axis over on the equivalence-partition surface AND peer to Self::unique_extremal_variants (set-level × Vec<Self> × modal-aggregation × direction-composition × union × unique-tie) one SURFACE axis over on the modal-aggregation matrix AND peer to Self::unique_missing_variant (set-level × Option<Self> × equivalence-partition × mult-band == 0 × unique-tie) one RETURN-SHAPE axis over (Option-return witness-when-unique → Vec-return singleton-or-empty-when-unique) AND peer to Self::has_unique_missing_variant (set-level × bool × equivalence-partition × mult-band == 0 × unique-tie) one RETURN-SHAPE axis over (bool uniqueness bit → Vec-return singleton-or-empty carrier of the same bit). Not a fresh substrate primitive on the index axis — the projection emerges from the boolean-guarded selection of the declaration-order miss-set witness-collection under the set-level miss-band uniqueness bit, collapsing to the empty Vec through the guard- arm when the bit falsifies.

fn unique_repeating_variants(items: &[Self]) -> Vec<Self>

The N-ARY ORDERING-AGNOSTIC “the unique strict-repeat witness as a singleton-or-empty Vec” projection — returns Self::repeating_variants iff items has a UNIQUE strict-repeat witness (Self::has_unique_repeating_variant holds) AND is the sole variant whose per-target multiplicity sits at >= 2, else vec![]. Computed as the just-lifted set-level strict-repeat uniqueness bit Self::has_unique_repeating_variant guarding the declaration-order strict-repeat witness-collection Self::repeating_variants: when the guard holds the collection is already a length-1 Vec by the guard’s own definition (count_repeating_variants == 1) and is lifted verbatim; when the guard falsifies the projection collapses to the EMPTY Vec through a zero-allocation ::std::vec::Vec::new() short-circuit. The Vec<Self>-RETURN UNIQUE-TIE SHARPENING corner CLOSING the strict- repeat arm of the (set-level × Vec<Self> × equivalence-partition × mult-band × unique-tie) row past the just-opened (mult == 0) miss-band arm Self::unique_missing_variants one MULTIPLICITY- BAND axis over on the equivalence-partition surface AND peer to Self::unique_repeating_variant (set-level × Option<Self> × equivalence-partition × mult-band >= 2 × unique-tie) one RETURN- SHAPE axis over (Option-return witness-when-unique → Vec-return singleton-or-empty-when-unique) AND peer to Self::has_unique_repeating_variant (set-level × bool × equivalence-partition × mult-band >= 2 × unique-tie) one RETURN- SHAPE axis over (bool uniqueness bit → Vec-return singleton-or- empty carrier of the same bit). Not a fresh substrate primitive on the index axis — the projection emerges from the boolean- guarded selection of the declaration-order strict-repeat witness- collection under the set-level strict-repeat uniqueness bit, collapsing to the empty Vec through the guard-arm when the bit falsifies.

fn unique_unique_variants(items: &[Self]) -> Vec<Self>

The N-ARY ORDERING-AGNOSTIC “the unique unique-band witness as a singleton-or-empty Vec” projection — returns Self::unique_variants iff items has a UNIQUE (mult == 1) witness (Self::has_unique_unique_variant holds) AND is the sole variant whose per-target multiplicity sits EXACTLY at 1, else vec![]. Computed as the just-lifted set-level unique-band uniqueness bit Self::has_unique_unique_variant guarding the declaration-order strict-uniqueness witness-collection Self::unique_variants: when the guard holds the collection is already a length-1 Vec by the guard’s own definition (count_unique_variants == 1) and is lifted verbatim; when the guard falsifies the projection collapses to the EMPTY Vec through a zero-allocation ::std::vec::Vec::new() short-circuit. The Vec<Self>-RETURN UNIQUE-TIE SHARPENING corner EXHAUSTIVELY CLOSING the middle (mult == 1) arm of the (set-level × Vec<Self> × equivalence-partition × mult-band × unique-tie) 3-corner row on the EQUIVALENCE-PARTITION surface AT ITS FINAL THIRD TILE past the (mult == 0) miss-band arm Self::unique_missing_variants AND the (mult >= 2) strict- repeat arm Self::unique_repeating_variants one MULTIPLICITY- BAND axis over. Peer to Self::unique_unique_variant (set- level × Option<Self> × equivalence-partition × mult == 1 × unique-tie) one RETURN-SHAPE axis over (Option-return witness- when-unique → Vec-return singleton-or-empty-when-unique) AND peer to Self::has_unique_unique_variant (set-level × bool × equivalence-partition × mult == 1 × unique-tie) one RETURN- SHAPE axis over (bool uniqueness bit → Vec-return singleton-or- empty carrier of the same bit). Not a fresh substrate primitive on the index axis — the projection emerges from the boolean- guarded selection of the declaration-order strict-uniqueness witness-collection under the set-level unique-band uniqueness bit, collapsing to the empty Vec through the guard-arm when the bit falsifies.

fn sorted_unique_missing_variants(items: &[Self]) -> Vec<Self>

The N-ARY ORDERING-AGNOSTIC “the unique miss-band witness in LEX order, as a singleton-or-empty Vec” projection — returns Self::sorted_missing_variants iff items has a UNIQUE absent variant (Self::has_unique_missing_variant holds), else vec![]. Computed as the just-lifted set-level miss-band uniqueness bit Self::has_unique_missing_variant guarding the LEX-ORDER miss-band witness-collection Self::sorted_missing_variants: when the guard holds the collection is already a length-1 Vec by the guard’s own definition (count_missing_variants == 1) and is lifted verbatim; when the guard falsifies the projection collapses to the EMPTY Vec through a zero-allocation ::std::vec::Vec::new() short-circuit. The LEX-ORDER Vec<Self>-RETURN MISS-BAND UNIQUE-TIE SHARPENING corner OPENING the LEX-ORDER (Vec<Self> × equivalence-partition × mult-band × unique-tie) row past the just-closed declaration- order trio (Self::unique_missing_variants, Self::unique_repeating_variants, Self::unique_unique_variants) one ORDERING axis over on the EQUIVALENCE-PARTITION surface, peer to Self::unique_missing_variants one ORDERING axis over (declaration-order → lex-order miss-band witness-collection- when-unique) AND peer to Self::sorted_missing_variants one UNIQUE-TIE-SHARPENING axis over (unsharpened lex-order miss-band witness-collection → uniqueness-gated lex-order miss-band witness-collection) AND peer to Self::sorted_unique_missing_variant one RETURN-SHAPE axis over (Option-return lex-first-witness-when-unique → Vec-return singleton-or-empty-when-unique) AND peer to Self::sorted_unique_extremal_variants one SURFACE axis over on the (Vec × sorted × unique-tie) face (EQUIVALENCE-PARTITION miss-band → MODAL-AGGREGATION union band). Not a fresh substrate primitive on the index axis — the projection emerges from the boolean-guarded selection of the just-lifted lex-order miss-band witness-collection under the set-level miss-band uniqueness bit, collapsing to the empty Vec through the guard-arm when the bit falsifies.

fn sorted_unique_repeating_variants(items: &[Self]) -> Vec<Self>

The N-ARY ORDERING-AGNOSTIC “the unique strict-repeat witness in LEX order, as a singleton-or-empty Vec” projection — returns Self::sorted_repeating_variants iff items has a UNIQUE strict-repeat variant (Self::has_unique_repeating_variant holds), else vec![]. Computed as the just-lifted set-level strict-repeat uniqueness bit Self::has_unique_repeating_variant guarding the LEX-ORDER strict-repeat witness-collection Self::sorted_repeating_variants: when the guard holds the collection is already a length-1 Vec by the guard’s own definition (count_repeating_variants == 1) and is lifted verbatim; when the guard falsifies the projection collapses to the EMPTY Vec through a zero-allocation ::std::vec::Vec::new() short-circuit. The LEX-ORDER Vec<Self>-RETURN STRICT-REPEAT UNIQUE-TIE SHARPENING corner CLOSING the strict-repeat arm of the LEX-ORDER (Vec<Self> × equivalence-partition × mult-band × unique-tie) row past the just-opened (mult == 0) miss-band arm Self::sorted_unique_missing_variants one MULTIPLICITY-BAND axis over on the EQUIVALENCE-PARTITION surface, peer to Self::unique_repeating_variants one ORDERING axis over (declaration-order → lex-order strict-repeat witness-collection- when-unique) AND peer to Self::sorted_repeating_variants one UNIQUE-TIE-SHARPENING axis over (unsharpened lex-order strict- repeat witness-collection → uniqueness-gated lex-order strict- repeat witness-collection) AND peer to Self::sorted_unique_repeating_variant one RETURN-SHAPE axis over (Option-return lex-first-witness-when-unique → Vec-return singleton-or-empty-when-unique) AND peer to Self::sorted_unique_extremal_variants one SURFACE axis over on the (Vec × sorted × unique-tie) face (EQUIVALENCE-PARTITION strict- repeat band → MODAL-AGGREGATION union band). Not a fresh substrate primitive on the index axis — the projection emerges from the boolean-guarded selection of the just-lifted lex-order strict- repeat witness-collection under the set-level strict-repeat uniqueness bit, collapsing to the empty Vec through the guard-arm when the bit falsifies.

fn sorted_unique_unique_variants(items: &[Self]) -> Vec<Self>

The N-ARY ORDERING-AGNOSTIC “the unique unique-band witness in LEX order, as a singleton-or-empty Vec” projection — returns Self::sorted_unique_variants iff items has a UNIQUE unique- band variant (Self::has_unique_unique_variant holds), else vec![]. Computed as the just-lifted set-level unique-band uniqueness bit Self::has_unique_unique_variant guarding the LEX-ORDER strict-uniqueness witness-collection Self::sorted_unique_variants: when the guard holds the collection is already a length-1 Vec by the guard’s own definition (count_unique_variants == 1) and is lifted verbatim; when the guard falsifies the projection collapses to the EMPTY Vec through a zero-allocation ::std::vec::Vec::new() short-circuit. The LEX-ORDER Vec<Self>-RETURN UNIQUE-BAND UNIQUE-TIE SHARPENING corner EXHAUSTIVELY CLOSING the middle (mult == 1) arm of the LEX-ORDER (Vec<Self> × equivalence-partition × mult-band × unique-tie) row AT ITS FINAL THIRD TILE past the (mult == 0) miss-band arm Self::sorted_unique_missing_variants AND the (mult >= 2) strict-repeat arm Self::sorted_unique_repeating_variants one MULTIPLICITY-BAND axis over on the EQUIVALENCE-PARTITION surface — the row is now the CANONICAL LEX-ORDER Vec<Self>-return unique-tie sharpening on the equivalence-partition surface, closed at its FINAL third tile AND EXHAUSTIVELY CLOSING the (Vec<Self> × equivalence- partition × mult-band × ordering × unique-tie) 3×2 face at its SIXTH tile. Peer to Self::unique_unique_variants one ORDERING axis over (declaration-order → lex-order unique-band witness- collection-when-unique) AND peer to Self::sorted_unique_variants one UNIQUE-TIE-SHARPENING axis over (unsharpened lex-order strict-uniqueness witness-collection → uniqueness-gated lex-order unique-band witness-collection) AND peer to Self::sorted_unique_unique_variant one RETURN-SHAPE axis over (Option-return lex-first-witness-when-unique → Vec- return singleton-or-empty-when-unique). Not a fresh substrate primitive on the index axis — the projection emerges from the boolean-guarded selection of the LEX-ORDER strict-uniqueness witness-collection under the set-level unique-band uniqueness bit, collapsing to the empty Vec through the guard-arm when the bit falsifies.

fn is_uniformly_repeating(items: &[Self]) -> bool

The N-ARY ORDERING-AGNOSTIC “every variant repeats?” predicate — true iff EVERY variant of Self::ALL appears AT LEAST TWICE in items, computed as the just-lifted set-level scalar Self::min_variant_count projection’s lower-bound test against 2. The BOOL-RETURN closer on the (set-level × bool × universal- lift × multiplicity-band) 4th-axis hypercube at the universal- lift >= 2 corner peer to the pre-existing (set-level × bool × universal-lift × multiplicity-band >= 1) Self::is_covering corner one MULTIPLICITY-BAND axis over AND peer to the pre- existing (set-level × bool × universal-lift × multiplicity-band <= 1) Self::is_pairwise_distinct corner one MULTIPLICITY- BAND axis over on the SAME universal-lift arm of the quantifier axis, AND the direct SET-LEVEL UNIVERSAL PEER of the (set-level × bool × existential-lift × multiplicity-band >= 2) Self::is_repeating_any corner one QUANTIFIER axis over on the SAME multiplicity band. Not a fresh substrate primitive on the index axis — the predicate emerges from ONE lower-bound scalar comparison against the substrate’s just-lifted set-level least-common-multiplicity aggregate.

fn present_labels(items: &[Self]) -> Vec<&'static str>

The N-ARY DECLARATION-ORDER “present labels” projection — the Vec<&'static str> label rendering of Self::present_variants under Self::label. Every label s in the returned vector is the canonical Self::label rendering of some variant present in items; the declaration order of Self::present_variants is preserved verbatim.

fn present_labels_joined(items: &[Self], sep: &str) -> String

The N-ARY DECLARATION-ORDER “present labels joined” projection — the String rendering of Self::present_labels joined by sep. Composes the substrate’s declaration-axis hit-label Vec-return primitive with the standard-library slice::join combinator so a passing implementor of Self::present_labels automatically satisfies this projection at every downstream site.

fn missing_labels(items: &[Self]) -> Vec<&'static str>

The N-ARY DECLARATION-ORDER “missing labels” projection — the Vec<&'static str> label rendering of Self::missing_variants under Self::label. Every label s in the returned vector is the canonical Self::label rendering of some variant ABSENT from items; the declaration order of Self::missing_variants is preserved verbatim. The DE MORGAN dual of Self::present_labels one partition-arm axis over on the label- return column of the equivalence-partition surface.

fn missing_labels_joined(items: &[Self], sep: &str) -> String

The N-ARY DECLARATION-ORDER “missing labels joined” projection — the String rendering of Self::missing_labels joined by sep. Composes the substrate’s declaration-axis miss-label Vec-return primitive with the standard-library slice::join combinator so a passing implementor of Self::missing_labels automatically satisfies this projection at every downstream site. The DE MORGAN dual of Self::present_labels_joined one partition-arm axis over on the String-return column of the equivalence-partition surface, and the DECLARATION-ORDER arm of the (present, absent) × (declaration, lex) 2×2 = 4-corner join-string face this projection closes past its Self::present_labels_joined sibling.

fn repeating_labels(items: &[Self]) -> Vec<&'static str>

The N-ARY DECLARATION-ORDER “repeating labels” projection — the Vec<&'static str> label rendering of Self::repeating_variants under Self::label. Every label s in the returned vector is the canonical Self::label rendering of some variant appearing STRICTLY MORE THAN ONCE (multiplicity >= 2) in items; the declaration order of Self::repeating_variants is preserved verbatim. The (multiplicity >= 2) STRICT-REPEAT band peer of Self::present_labels (multiplicity >= 1) and Self::missing_labels (multiplicity == 0) one MULTIPLICITY- BAND axis over on the equivalence-partition surface — OPENS the (repeating, Vec<&'static str> label, declaration-order) corner past the pre-existing (present, Vec<&'static str> label, declaration-order) and (absent, Vec<&'static str> label, declaration-order) doublet on the label-return column.

fn repeating_labels_joined(items: &[Self], sep: &str) -> String

The N-ARY DECLARATION-ORDER “repeating labels joined” projection — the String rendering of Self::repeating_labels joined by sep. Composes the substrate’s declaration-axis strict-repeat label-Vec primitive with the standard-library slice::join combinator so a passing implementor of Self::repeating_labels automatically satisfies this projection at every downstream site. The (multiplicity >= 2) STRICT-REPEAT band peer of Self::present_labels_joined (multiplicity >= 1) and Self::missing_labels_joined (multiplicity == 0) one MULTIPLICITY-BAND axis over on the declaration-order String- return column of the equivalence-partition surface — EXHAUSTIVELY CLOSES the (partition-band × String × declaration-order) 3-tile row at its FINAL third tile past the pre-existing (present, String, declaration) and (absent, String, declaration) doublet.

fn sorted_present_labels(items: &[Self]) -> Vec<&'static str>

The N-ARY LEX-ORDER “present labels” projection — the Vec<&'static str> label rendering of Self::sorted_present_variants under Self::label. Every label s in the returned vector is the canonical Self::label rendering of some variant present in items; the lex order of Self::sorted_present_variants is preserved verbatim. The LEX-ORDER peer of Self::present_labels on the (declaration, lex) ordering axis of the label-return column of the equivalence-partition surface — opens the lex arm past the declaration arm the sibling Self::present_labels closed.

fn sorted_present_labels_joined(items: &[Self], sep: &str) -> String

The N-ARY LEX-ORDER “present labels joined” projection — the String rendering of Self::sorted_present_labels joined by sep. Composes the substrate’s lex-axis hit-label Vec-return primitive with the standard-library slice::join combinator so a passing implementor of Self::sorted_present_labels automatically satisfies this projection at every downstream site. The LEX-ORDER peer of Self::present_labels_joined one ordering axis over on the (declaration, lex) axis of the join-string column of the equivalence-partition surface — opens the lex arm past the declaration arm the sibling Self::present_labels_joined closed.

fn sorted_missing_labels(items: &[Self]) -> Vec<&'static str>

The N-ARY LEX-ORDER “missing labels” projection — the Vec<&'static str> label rendering of Self::sorted_missing_variants under Self::label. Every label s in the returned vector is the canonical Self::label rendering of some variant ABSENT from items; the lex order of Self::sorted_missing_variants is preserved verbatim. The DE MORGAN dual of Self::sorted_present_labels one partition-arm axis over on the lex-order arm of the label- return column of the equivalence-partition surface, and the LEX-ORDER peer of Self::missing_labels on the (declaration, lex) ordering axis.

fn sorted_missing_labels_joined(items: &[Self], sep: &str) -> String

The N-ARY LEX-ORDER “missing labels joined” projection — the String rendering of Self::sorted_missing_labels joined by sep. Composes the substrate’s lex-axis miss-label Vec-return primitive with the standard-library slice::join combinator so a passing implementor of Self::sorted_missing_labels automatically satisfies this projection at every downstream site. The FOURTH corner CLOSING the (partition-arm × ordering) 2×2 = 4-corner join-string face on the label-join column of the equivalence-partition surface past the pre-existing corners at Self::present_labels_joined (present × decl), Self::missing_labels_joined (absent × decl), and Self::sorted_present_labels_joined (present × lex). The LEX-ORDER peer of Self::missing_labels_joined one ordering axis over, and the DE MORGAN dual of Self::sorted_present_labels_joined one partition-arm axis over.

fn sorted_repeating_labels(items: &[Self]) -> Vec<&'static str>

The N-ARY LEX-ORDER “repeating labels” projection — the Vec<&'static str> label rendering of Self::sorted_repeating_variants under Self::label. Every label s in the returned vector is the canonical Self::label rendering of some variant whose per-target multiplicity in items is >= 2; the lex order of Self::sorted_repeating_variants is preserved verbatim. The LEX-ORDER peer of Self::repeating_labels one ORDERING axis over on the equivalence-partition surface — opens the lex arm of the (strict-repeat × Vec<&'static str>) column past the declaration arm the sibling Self::repeating_labels closed, mirroring Self::sorted_present_labels opening its lex arm past Self::present_labels and Self::sorted_missing_labels opening its lex arm past Self::missing_labels.

fn sorted_repeating_labels_joined(items: &[Self], sep: &str) -> String

The N-ARY LEX-ORDER “repeating labels joined” projection — the String rendering of Self::sorted_repeating_labels joined by sep. Composes the substrate’s lex-axis strict-repeat-label Vec-return primitive with the standard-library slice::join combinator so a passing implementor of Self::sorted_repeating_labels automatically satisfies this projection at every downstream site. The SIXTH corner EXHAUSTIVELY CLOSING the (partition-band × ordering) 3×2 = 6-corner join-string face on the label-join column of the equivalence-partition surface past the pre-existing quintet at Self::present_labels_joined (present × decl), Self::missing_labels_joined (absent × decl), Self::repeating_labels_joined (repeating × decl), Self::sorted_present_labels_joined (present × lex), and Self::sorted_missing_labels_joined (absent × lex). The LEX-ORDER peer of Self::repeating_labels_joined one ORDERING axis over, and the mult-band >= 2 peer of Self::sorted_missing_labels_joined + Self::sorted_present_labels_joined one PARTITION-BAND axis over on the lex arm.

fn present_indices(items: &[Self]) -> Vec<usize>

The N-ARY DECLARATION-ORDER “present indices” projection — the Vec<usize> Self::ALL-index rendering of Self::present_variants under Self::index_of. Every usize i in the returned vector is the Self::ALL-position of some variant present in items; the declaration order of Self::present_variants is preserved verbatim, so the returned indices form a STRICTLY ASCENDING subsequence of 0..Self::CARDINALITY. The VEC-INDEX-RETURN present-arm opener on the (Vec, Vec<&’static str>, Vec) return-shape column trio of the equivalence-partition surface, positioned past the exhaustively-closed 4-corner (Vec-variant, Vec-label) × (declaration, lex) label-and-variant face the prior lifts Self::present_variants, Self::missing_variants, Self::sorted_present_variants, Self::sorted_missing_variants, Self::present_labels, Self::missing_labels, Self::sorted_present_labels, Self::sorted_missing_labels closed.

fn missing_indices(items: &[Self]) -> Vec<usize>

The N-ARY DECLARATION-ORDER “missing indices” projection — the Vec<usize> Self::ALL-index rendering of Self::missing_variants under Self::index_of. Every usize i in the returned vector is the Self::ALL-position of some variant ABSENT from items; the declaration order of Self::missing_variants is preserved verbatim, so the returned indices form a STRICTLY ASCENDING subsequence of 0..Self::CARDINALITY. The DE MORGAN dual of Self::present_indices one partition-arm axis over on the index-return column of the equivalence-partition surface.

fn sorted_present_indices(items: &[Self]) -> Vec<usize>

The N-ARY LEX-ORDER “present indices” projection — the Vec<usize> Self::ALL-index rendering of Self::sorted_present_variants under Self::index_of. Every usize i in the returned vector is the Self::ALL-position of some variant present in items; the lex order of Self::sorted_present_variants is preserved verbatim, so the returned indices form a subsequence of Self::sorted_variants-under-Self::index_of (whose declaration-axis peer Self::present_indices is a subsequence of 0..Self::CARDINALITY in strictly ascending order). The LEX-ORDER peer of Self::present_indices on the (declaration, lex) ordering axis of the index-return column of the equivalence-partition surface.

fn sorted_missing_indices(items: &[Self]) -> Vec<usize>

The N-ARY LEX-ORDER “missing indices” projection — the Vec<usize> Self::ALL-index rendering of Self::sorted_missing_variants under Self::index_of. Every usize i in the returned vector is the Self::ALL-position of some variant ABSENT from items; the lex order of Self::sorted_missing_variants is preserved verbatim. The DE MORGAN dual of Self::sorted_present_indices one partition-arm axis over on the lex-order arm of the index-return column of the equivalence-partition surface, and the LEX-ORDER peer of Self::missing_indices on the (declaration, lex) ordering axis — EXHAUSTIVELY CLOSES the (index-return × ordering) 2×2 = 4-corner face on the index-return column past the three prior corners.

fn repeating_indices(items: &[Self]) -> Vec<usize>

The N-ARY DECLARATION-ORDER “repeating indices” projection — the Vec<usize> Self::ALL-index rendering of Self::repeating_variants under Self::index_of. Every usize i in the returned vector is the Self::ALL-position of some variant appearing STRICTLY MORE THAN ONCE (multiplicity >= 2) in items; the declaration order of Self::repeating_variants is preserved verbatim, so the returned indices form a STRICTLY ASCENDING subsequence of 0..Self::CARDINALITY. The (multiplicity >= 2) STRICT-REPEAT band peer of Self::present_indices (multiplicity >= 1) and Self::missing_indices (multiplicity == 0) one MULTIPLICITY- BAND axis over on the index-return column of the equivalence- partition surface — OPENS the (repeating, Vec<usize> index, declaration-order) corner past the exhaustively-closed (index-return × ordering) 2×2 = 4-corner face on the (present, absent) doublet that Self::present_indices, Self::missing_indices, Self::sorted_present_indices, Self::sorted_missing_indices closed. Peer to Self::repeating_labels one RETURN-SHAPE column over on the same multiplicity band — same partition-arm, same declaration order, different Vec-return projection (Vec<usize> vs Vec<&'static str>).

fn sorted_repeating_indices(items: &[Self]) -> Vec<usize>

The N-ARY LEX-ORDER “repeating indices” projection — the Vec<usize> Self::ALL-index rendering of Self::sorted_repeating_variants under Self::index_of. Every usize i in the returned vector is the Self::ALL- position of some variant appearing STRICTLY MORE THAN ONCE (multiplicity >= 2) in items; the lex order of Self::sorted_repeating_variants is preserved verbatim, so the returned indices form a canonical LEX-order subsequence of Self::sorted_variants under Self::index_of — which is NOT in general a monotone subsequence of 0..Self::CARDINALITY on implementors whose declaration order diverges from Self::sorted_labels. The LEX-ORDER peer of Self::repeating_indices one ORDERING axis over on the equivalence-partition surface — EXHAUSTIVELY CLOSES the (partition-band × ordering) 3×2 = 6-corner face on the index-return column at its FINAL sixth tile past the pre- existing quintet of Self::present_indices, Self::missing_indices, Self::repeating_indices, Self::sorted_present_indices, and Self::sorted_missing_indices, mirroring the exhaustively-closed (partition-band × ordering) 3×2 face on the sibling label-Vec-return column that Self::sorted_repeating_labels closed one return-shape axis over.

fn present_indices_joined(items: &[Self], sep: &str) -> String

The N-ARY DECLARATION-ORDER “present indices joined” projection — the String rendering of Self::present_indices under usize::to_string joined by sep. Composes the substrate’s declaration-axis hit-index Vec-return primitive with the per-slot usize-to-String projection and the standard-library slice::join combinator so a passing implementor of Self::present_indices automatically satisfies this projection at every downstream site. OPENS the (indices, joined) column of the (partition-band × ordering × return-shape) 3×2×2 = 12-tile equivalence-partition index-aggregation surface past the exhaustively-closed 6-corner (partition-band × ordering) Vec-return face at Self::present_indices / Self::missing_indices / Self::repeating_indices / Self::sorted_present_indices / Self::sorted_missing_indices / Self::sorted_repeating_indices one RETURN-SHAPE axis over.

fn missing_indices_joined(items: &[Self], sep: &str) -> String

The N-ARY DECLARATION-ORDER “missing indices” join-string projection — the Self::missing_indices Vec-return miss- witness index list stringified per slot under usize::to_string and threaded into a single String under the caller’s separator.

fn repeating_indices_joined(items: &[Self], sep: &str) -> String

The N-ARY DECLARATION-ORDER “repeating indices” join-string projection — the Self::repeating_indices Vec-return strict-repeat-witness index list stringified per slot under usize::to_string and threaded into a single String under the caller’s separator.

fn sorted_present_indices_joined(items: &[Self], sep: &str) -> String

The N-ARY LEX-ORDER “present indices joined” projection — the String rendering of Self::sorted_present_indices under usize::to_string joined by sep. Composes the substrate’s lex-axis hit-index Vec-return primitive with the per-slot usize-to-String projection and the standard-library slice::join combinator so a passing implementor of Self::sorted_present_indices automatically satisfies this projection at every downstream site. OPENS the LEX-ORDER row of the (partition-band × ordering × join-string) 3×2 = 6-corner face on the index-join column of the equivalence-partition index-aggregation surface past the just-closed declaration-order row at Self::present_indices_joined, Self::missing_indices_joined, and Self::repeating_indices_joined one ORDERING axis over.

fn sorted_missing_indices_joined(items: &[Self], sep: &str) -> String

The N-ARY LEX-ORDER “missing indices joined” projection — the String rendering of Self::sorted_missing_indices under usize::to_string joined by sep. Composes the substrate’s lex-axis miss-index Vec-return primitive with the per-slot usize-to-String projection and the standard-library slice::join combinator so a passing implementor of Self::sorted_missing_indices automatically satisfies this projection at every downstream site. CLOSES the miss-arm one PARTITION-BAND axis over on the LEX-ORDER row of the (partition- band × ordering × join-string) 3×2 = 6-corner face on the index- join column of the equivalence-partition index-aggregation surface past the just-opened Self::sorted_present_indices_joined present-arm one PARTITION-BAND axis over.

fn unique_missing_labels(items: &[Self]) -> Vec<&'static str>

The N-ARY DECLARATION-ORDER “the unique miss-band witness as a singleton-or-empty label Vec” projection — the Vec<&'static str> label rendering of Self::unique_missing_variants under Self::label. Every label s in the returned vector is the canonical Self::label rendering of some variant ABSENT from items AND the SOLE absent variant (the miss-band uniqueness guard Self::has_unique_missing_variant holds). When the guard falsifies the projection collapses to the EMPTY Vec through a zero-allocation short-circuit inherited from Self::unique_missing_variants.

fn unique_repeating_labels(items: &[Self]) -> Vec<&'static str>

The N-ARY DECLARATION-ORDER “the unique strict-repeat witness as a singleton-or-empty label Vec” projection — the Vec<&'static str> label rendering of Self::unique_repeating_variants under Self::label. Every label s in the returned vector is the canonical Self::label rendering of some variant that appears TWO-OR-MORE times in items AND is the SOLE strict-repeat variant (the strict-repeat uniqueness guard Self::has_unique_repeating_variant holds). When the guard falsifies the projection collapses to the EMPTY Vec through a zero-allocation short-circuit inherited from Self::unique_repeating_variants.

fn unique_unique_labels(items: &[Self]) -> Vec<&'static str>

The N-ARY DECLARATION-ORDER “the unique unique-band witness as a singleton-or-empty label Vec” projection — the Vec<&'static str> label rendering of Self::unique_unique_variants under Self::label. Every label s in the returned vector is the canonical Self::label rendering of some variant that appears EXACTLY ONCE in items AND is the SOLE unique-band variant (the unique-band uniqueness guard Self::has_unique_unique_variant holds). When the guard falsifies the projection collapses to the EMPTY Vec through a zero-allocation short-circuit inherited from Self::unique_unique_variants.

fn unique_missing_labels_joined(items: &[Self], sep: &str) -> String

The N-ARY DECLARATION-ORDER “the unique miss-band witness as a singleton-or-empty joined-label String” projection — the String rendering of Self::unique_missing_labels joined by sep. Composes the substrate’s just-lifted uniqueness-gated miss-band label-Vec primitive with the standard-library slice::join combinator so a passing implementor of Self::unique_missing_labels automatically satisfies this projection at every downstream site. When the miss-band uniqueness guard Self::has_unique_missing_variant holds, the projection returns the sole absent variant’s label as a bare String (no separator surfaces because the joined slice is a singleton); when the guard falsifies, the projection collapses to the EMPTY String through a zero-allocation short-circuit inherited from Self::unique_missing_labels.

fn unique_repeating_labels_joined(items: &[Self], sep: &str) -> String

The N-ARY DECLARATION-ORDER “the unique strict-repeat witness as a singleton-or-empty joined-label String” projection — the String rendering of Self::unique_repeating_labels joined by sep. Composes the substrate’s just-lifted uniqueness-gated strict-repeat label-Vec primitive with the standard-library slice::join combinator so a passing implementor of Self::unique_repeating_labels automatically satisfies this projection at every downstream site. When the strict-repeat uniqueness guard Self::has_unique_repeating_variant holds, the projection returns the sole repeated variant’s label as a bare String (no separator surfaces because the joined slice is a singleton); when the guard falsifies, the projection collapses to the EMPTY String through a zero-allocation short-circuit inherited from Self::unique_repeating_labels.

fn unique_unique_labels_joined(items: &[Self], sep: &str) -> String

The N-ARY DECLARATION-ORDER “the unique unique-band witness as a singleton-or-empty joined-label String” projection — the String rendering of Self::unique_unique_labels joined by sep. Composes the substrate’s just-lifted uniqueness-gated unique-band label-Vec primitive with the standard-library slice::join combinator so a passing implementor of Self::unique_unique_labels automatically satisfies this projection at every downstream site. When the unique-band uniqueness guard Self::has_unique_unique_variant holds, the projection returns the sole once-occurring variant’s label as a bare String (no separator surfaces because the joined slice is a singleton); when the guard falsifies, the projection collapses to the EMPTY String through a zero-allocation short-circuit inherited from Self::unique_unique_labels.

fn is_between(self, lo: Self, hi: Self) -> bool

The declaration-order INCLUSIVE-both closed-range containment predicate — true iff self sits in the closed range [lo, hi] of Self::ALL’s declaration order, false when self sits strictly before lo OR strictly after hi. The TERNARY-arity opener on the closed-set surface, past the exhaustively-closed 8-corner (ordering × direction × strictness) 2×2×2 pairwise-comparison hypercube (78)+(79)+(80)+(81) — opens the arity axis one step further from binary pairwise-comparison to ternary closed-range containment.

fn is_sorted_between(self, lo: Self, hi: Self) -> bool

The lex-order INCLUSIVE-both closed-range containment predicate — true iff self sits in the closed range [lo, hi] of the lex-order Self::sorted_labels, false when self sits strictly before lo OR strictly after hi in lex order. The lex-ordering peer of Self::is_between on the (declaration, lex) ordering axis of the ternary closed- range containment surface.

fn is_strictly_between(self, lo: Self, hi: Self) -> bool

The declaration-order EXCLUSIVE-both closed-range containment predicate — true iff self sits STRICTLY inside the open range (lo, hi) of the declaration-order Self::ALL, false when self coincides with EITHER endpoint OR sits outside. The strict-precedence peer of Self::is_between on the (endpoint-inclusivity) axis of the ternary closed-range containment surface — opens the (exclusive-both) corner of the 4-corner (ordering × endpoint-inclusivity-flavor) matrix past the (inclusive-both) corner (82)+(83) Self::is_between / Self::is_sorted_between closed.

fn is_sorted_strictly_between(self, lo: Self, hi: Self) -> bool

The lex-order EXCLUSIVE-both closed-range containment predicate — true iff self sits STRICTLY inside the open range (lo, hi) of the lex-order Self::sorted_labels, false when self coincides with EITHER endpoint OR sits outside in lex order. The lex-ordering peer of Self::is_strictly_between on the (declaration, lex) ordering axis of the ternary strict- open-range containment surface.

fn is_right_half_open_between(self, lo: Self, hi: Self) -> bool

The declaration-order RIGHT-HALF-OPEN closed-range containment predicate — true iff self sits in the half-open range [lo, hi) of the declaration-order Self::ALL, false when self coincides with the upper endpoint hi, sits strictly before lo, OR sits strictly after hi. The “canonical half-open” arm on the (endpoint-inclusivity-flavor) axis of the ternary closed-range containment surface — mirroring std::ops::Range::contains, Python range(), and the standard mathematical [lo, hi) interval notation where the RIGHT endpoint is the OPEN one.

fn is_sorted_right_half_open_between(self, lo: Self, hi: Self) -> bool

The lex-order RIGHT-HALF-OPEN closed-range containment predicate — true iff self sits in the half-open range [lo, hi) of the lex-order Self::sorted_labels, false when self coincides with the upper endpoint hi, sits strictly before lo OR strictly after hi in lex order. The lex-ordering peer of Self::is_right_half_open_between on the (declaration, lex) ordering axis of the ternary right- half-open-range containment surface.

fn is_left_half_open_between(self, lo: Self, hi: Self) -> bool

The declaration-order LEFT-HALF-OPEN closed-range containment predicate — true iff self sits in the half-open range (lo, hi] of the declaration-order Self::ALL, false when self coincides with the lower endpoint lo, sits strictly before lo, OR sits strictly after hi. The MIRROR asymmetric-mix on the (endpoint-inclusivity-flavor) axis of the ternary closed-range containment surface — mirroring the mathematical (lo, hi] interval notation where the LEFT endpoint is the OPEN one, and Kotlin’s absent-but-natural v in lo<..hi left-exclusive-range shape (Kotlin exposes ..< for right-half-open but not the mirror; the substrate closes both flavors symmetrically).

fn is_sorted_left_half_open_between(self, lo: Self, hi: Self) -> bool

The lex-order LEFT-HALF-OPEN closed-range containment predicate — true iff self sits in the half-open range (lo, hi] of the lex-order Self::sorted_labels, false when self coincides with the lower endpoint lo, sits strictly before lo OR strictly after hi in lex order. The lex-ordering peer of Self::is_left_half_open_between on the (declaration, lex) ordering axis of the ternary left- half-open-range containment surface.

fn clamp(self, lo: Self, hi: Self) -> Self

The declaration-order ternary CLAMP projection — the value-projection sibling of Self::is_between on the (return-shape) axis of the ternary closed-range surface. Given a well-formed range [lo, hi] with lo.precedes_or_equal(hi), projects self INTO the range by (a) returning lo when self strictly precedes lo, (b) returning hi when hi strictly precedes self, and (c) returning self unchanged otherwise. The typed value-projection dual of the eight-corner (ordering × endpoint-inclusivity-flavor) bool-return ternary containment hypercube (is_between (82)+(83), is_strictly_between (84)+(85), is_right_half_open_between (86)+(87), is_left_half_open_between (88)+(89)) — where the eight bool-return corners answer “does self sit in the range?”, this projection answers “what variant IN the range does self project to?”.

fn sorted_clamp(self, lo: Self, hi: Self) -> Self

The lex-order ternary CLAMP projection — the value-projection sibling of Self::is_sorted_between on the (return-shape) axis of the ternary closed-range surface. Given a well-formed lex-range [lo, hi] with lo.sorted_precedes_or_equal(hi), projects self INTO the lex-range by returning lo when self strictly lex-precedes lo, returning hi when hi strictly lex-precedes self, and returning self unchanged otherwise. The lex-ordering peer of Self::clamp on the (declaration, lex) ordering axis of the ternary Self-return closed-range surface.

fn clamp_label(self, lo: Self, hi: Self) -> &'static str

The canonical &'static str LABEL of the declaration-order ternary-CLAMP projection of self into the closed range [lo, hi] — the label of Self::clamp projected through Self::label. Returns &'static str, never Option<&'static str>: the ternary clamp projection is TOTAL on well-formed ranges (every well-formed triple lands on a variant in the closed range, and every variant carries a canonical label).

fn sorted_clamp_label(self, lo: Self, hi: Self) -> &'static str

The canonical &'static str LABEL of the lex-order ternary- CLAMP projection of self into the closed lex-range [lo, hi] — the label of Self::sorted_clamp projected through Self::label. Returns &'static str, never Option<&'static str>.

fn clamp_index(self, lo: Self, hi: Self) -> usize

The usize DECLARATION-ORDER INDEX of the declaration-order ternary-CLAMP projection of self into the closed range [lo, hi] — the declaration-order position of Self::clamp projected through Self::index_of. Returns usize, never Option<usize>: the ternary clamp projection is TOTAL on well-formed ranges, and every variant carries a declaration-order slot.

fn sorted_clamp_index(self, lo: Self, hi: Self) -> usize

The usize LEXICOGRAPHIC-ORDER INDEX of the lex-order ternary-CLAMP projection of self into the closed lex-range [lo, hi] — the lex position of Self::sorted_clamp projected through Self::sorted_index_of. Returns usize, never Option<usize>.

fn saturating_next(self) -> Self

The declaration-order neighbor immediately AFTER self in Self::ALL, SATURATING at self at the tail — the third arm of the (boundary-behavior) axis on the closed-set forward- declaration-neighbor surface past the pre-existing (Option-typed-bounded, Self-typed-wrapping) partition: Self::next returns None at the tail, Self::cycle_next FOLDS the tail-endpoint boundary onto Self::first, and THIS method PINS self at the tail-endpoint boundary — the “stay-at-boundary” arm of the three-way boundary-behavior partition. Returns Self, never Option<Self>: the saturating arm folds the tail-endpoint boundary onto self itself rather than wrapping to the head (Self::cycle_next) or leaving the None the bounded arm (Self::next) returns.

fn saturating_prev(self) -> Self

The declaration-order neighbor immediately BEFORE self in Self::ALL, SATURATING at self at the head — self.prev().unwrap_or(self). Returns Self, never Option<Self>: the saturating arm folds the head-endpoint boundary onto self itself rather than wrapping to the tail (Self::cycle_prev) or leaving the None the bounded arm (Self::prev) returns.

fn sorted_saturating_next(self) -> Self

The lex-order neighbor immediately AFTER self in Self::sorted_variants, SATURATING at self at the lex tail — self.sorted_next().unwrap_or(self). Returns Self, never Option<Self>: the saturating arm folds the lex-tail-endpoint boundary onto self itself rather than wrapping to the lex head (Self::cycle_sorted_next) or leaving the None the bounded lex arm (Self::sorted_next) returns.

fn sorted_saturating_prev(self) -> Self

The lex-order neighbor immediately BEFORE self in Self::sorted_variants, SATURATING at self at the lex head — self.sorted_prev().unwrap_or(self). Returns Self, never Option<Self>: the saturating arm folds the lex-head-endpoint boundary onto self itself rather than wrapping to the lex tail (Self::cycle_sorted_prev) or leaving the None the bounded lex arm (Self::sorted_prev) returns.

fn saturating_next_label(self) -> &'static str

The canonical &'static str LABEL of the declaration-order neighbor immediately AFTER self in Self::ALL, SATURATING at Self::label at the tail — the label of Self::saturating_next projected through Self::label. Returns &'static str, never Option<&'static str>: the saturating arm folds the tail-endpoint boundary onto self’s OWN label rather than wrapping to Self::first_label (the wrapping arm’s Self::cycle_next_label fold) or leaving the None the bounded arm (Self::next_label) returns.

fn saturating_prev_label(self) -> &'static str

The canonical &'static str LABEL of the declaration-order neighbor immediately BEFORE self in Self::ALL, SATURATING at Self::label at the head — the label of Self::saturating_prev projected through Self::label. Returns &'static str, never Option<&'static str>.

fn sorted_saturating_next_label(self) -> &'static str

The canonical &'static str LABEL of the lexicographic-order neighbor immediately AFTER self in Self::sorted_variants, SATURATING at Self::label at the lex tail — the label of Self::sorted_saturating_next projected through Self::label. Returns &'static str, never Option<&'static str>.

fn sorted_saturating_prev_label(self) -> &'static str

The canonical &'static str LABEL of the lexicographic-order neighbor immediately BEFORE self in Self::sorted_variants, SATURATING at Self::label at the lex head — the label of Self::sorted_saturating_prev projected through Self::label. Returns &'static str, never Option<&'static str>.

fn saturating_next_index(self) -> usize

The usize DECLARATION-ORDER INDEX of the neighbor immediately AFTER self in Self::ALL, SATURATING at Self::index_of(self) at the tail — the declaration-order position of Self::saturating_next projected through Self::index_of. Returns usize, never Option<usize>: the saturating arm folds the tail-endpoint boundary onto self’s OWN slot rather than wrapping to 0 (the wrapping arm’s Self::cycle_next_index fold) or leaving the None the bounded arm (Self::next_index) returns.

fn saturating_prev_index(self) -> usize

The usize DECLARATION-ORDER INDEX of the neighbor immediately BEFORE self in Self::ALL, SATURATING at Self::index_of(self) at the head — the declaration-order position of Self::saturating_prev projected through Self::index_of. Returns usize, never Option<usize>.

fn sorted_saturating_next_index(self) -> usize

The usize LEXICOGRAPHIC-ORDER INDEX of the neighbor immediately AFTER self in Self::sorted_variants, SATURATING at Self::sorted_index_of(self) at the lex tail — the lex position of Self::sorted_saturating_next projected through Self::sorted_index_of. Returns usize, never Option<usize>.

fn sorted_saturating_prev_index(self) -> usize

The usize LEXICOGRAPHIC-ORDER INDEX of the neighbor immediately BEFORE self in Self::sorted_variants, SATURATING at Self::sorted_index_of(self) at the lex head — the lex position of Self::sorted_saturating_prev projected through Self::sorted_index_of. Returns usize, never Option<usize>.

impl Copy for UnquoteForm

impl Debug for UnquoteForm

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Display for UnquoteForm

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Eq for UnquoteForm

impl FromStr for UnquoteForm

type Err = UnknownUnquoteForm

The associated error which can be returned from parsing.

fn from_str(s: &str) -> Result<Self, Self::Err>

Parses a string s to return a value of this type.

impl PartialEq for UnquoteForm

fn eq(&self, other: &UnquoteForm) -> bool

Equality operator ==.

fn ne(&self, other: &Rhs) -> bool

Inequality operator !=.

impl StructuralPartialEq for UnquoteForm