Crate khive_fold 

khive-fold: Cognitive primitives — Fold, Anchor, Objective, Selector.

Four cognitive primitives that form the “paper-folding” operation:

• Fold: entries → derived state (deterministic reduce)
• Anchor: causal graph traversal (provenance chains)
• Objective: score candidates and select best
• Selector: budget-constrained pack (many → subset)

Plus deterministic ordering primitives, composition combinators, and common strategies (Recency, Relevance, Weighted, etc.).

Quick Start

use khive_fold::{fold_fn, Fold, FoldContext};

let counter = fold_fn(
    |_ctx| 0usize,
    |count, _entry: &i32, _ctx| count + 1,
);

let entries = [1, 2, 3, 4, 5];
let result = counter.derive(entries.iter(), &FoldContext::new());
assert_eq!(result.state, 5);

Re-exports

pub use anchor::Anchor;

pub use anchor::AnchorGraph;

pub use anchor::AnchorRef;

pub use anchor::BfsAnchor;

pub use selector::GreedySelector;

pub use selector::Selector;

pub use selector::SelectorInput;

pub use selector::SelectorOutput;

pub use selector::SelectorWeights;

pub use objective::builtin::FirstMatchObjective;

pub use objective::builtin::HasImportance;

pub use objective::builtin::HasTimestamp;

pub use objective::builtin::ImportanceObjective;

pub use objective::builtin::MaxScoreObjective;

pub use objective::builtin::RecencyObjective;

pub use objective::builtin::RelevanceObjective;

pub use objective::builtin::ThresholdObjective;

pub use objective::compose::ConsensusObjective;

pub use objective::compose::NegateObjective;

pub use objective::compose::PriorityObjective;

pub use objective::compose::ScaleObjective;

pub use objective::compose::UnionObjective;

pub use objective::compose::WeightedObjective;

pub use objective::error::ObjectiveError;

pub use objective::error::ObjectiveResult;

pub use objective::objective_fn;

pub use objective::DeterministicObjective;

pub use objective::Objective;

pub use objective::ObjectiveContext;

pub use objective::Selection;

pub use ordering::canonical_f32;

pub use ordering::canonical_f64;

pub use ordering::cmp_asc_score_then_id;

pub use ordering::cmp_desc_score_then_id;

pub use ordering::HasId;

pub use ordering::ScoredEntry;

Modules

anchor

Anchor: causal structure.

objective

Objective function framework — scoring, selection, composition.

ordering

Deterministic ordering primitives for objective functions

selector

Selector: many → subset under budget.

Structs

AnyFold

A zero-allocation existential fold with a function-pointer predicate.

CountFold

A zero-allocation count fold.

DeterministicScore

DualFold

Dual fold — run two folds independently over the same entries.

FilterCountFold

A zero-allocation count fold with a function-pointer predicate.

FilterFold

Filter fold — only process entries matching a predicate.

FnFold

Helper to create a fold from closures.

FoldContext

Context for fold operations.

FoldOutcome

Outcome of a fold operation.

MapFold

Map fold — transform entries before folding.

QuantKey

8-byte packed sort key: i32 quantized score + u32 ID prefix.

Ranked

Ranked item: score descending, ID ascending for ties.

SequentialFold

Sequential fold — run one fold, then use its output to inform another.

SharedJson

Shared JSON value backed by Arc<serde_json::Value>.

SumI64Fold

A zero-allocation i64 summation fold with a function-pointer projection.

Enums

CommonFold

Enum-dispatch fold for common patterns that would otherwise use Box<dyn Fold>.

CommonFoldState

Unified state returned by CommonFold.

FoldError

Errors that can occur in fold operations

FoldFailure

Failure returned by fallible fold operations.

Traits

Fold

Core fold trait for deriving state from entries.

TryFold

Fallible fold step API for reducers that can reject invalid state shapes.

Functions

cmp_asc_then_id

Compare scores ascending, lower ID wins ties.

cmp_desc_then_id

Compare scores descending, lower ID wins ties.

filter

Helper to create a filter fold.

fold_fn

Create a fold from just initial and step functions (no finalize).

map

Helper to create a map fold.

Type Aliases

BoxedFold

A boxed fold for dynamic dispatch.

FoldResult

Result type for fold operations

FoldResultType

Result type for fold operations