Crate lemma 

Lemma Engine

Rules for man and machine

Consumer API: load → list → show / source → run.

Modules

deps

Dependency layout under <workdir>/lemma_deps/, shared by CLI fetch and LSP.

Structs

Cause

Context

Ordered store of specs keyed by (repository, name) and grouped into LemmaSpecSets.

DataEntry

One data entry in a Show.

DataPath

Resolved path to a data (created during planning from AST DataReference)

DateTimeValue

Engine

Engine for evaluating Lemma rules.

ErrorDetails

Detailed error information with optional source location.

Errors

Load failure: errors plus the source texts we attempted to load.

Explanation

LemmaBase

The LemmaBase registry fetches Lemma source text from LemmaBase.

LemmaRepository

A Lemma repository header. Identity carrier; never owns specs.

LemmaSpec

A Lemma spec containing data and rules.

LemmaSpecSet

All spec versions sharing a (repository, name) identity, keyed by effective_from.

LemmaType

Resolved type after planning

Lexer

ListedSpec

Listed spec row from Engine::list.

LiteralValue

Literal value with type. The single value type in semantics.

MeasureUnit

A single unit within a Measure type.

MeasureUnits

ParseResult

RatioUnit

RatioUnits

RegistryBundle

A bundle of Lemma source text returned by the Registry.

RegistryError

An error returned by a Registry implementation.

ResolvedRepository

Repository group from Engine::list.

ResourceLimits

Limits to prevent abuse and enable predictable resource usage

Response

Response from evaluating a Lemma spec

RuleResult

Result of evaluating a single rule. Struct fields match the API JSON shape.

SerializedConversionTraceStep

Show

Consumer [Engine::show] result: data used by the spec’s rules, local rule result types, and resolved temporal window. Source: [Engine::source].

ShowVersion

Half-open [effective_from, effective_to) for one loaded temporal row.

Source

Positional source location: source id and span.

Span

Span representing a location in source code

SpecRef

A spec reference written in source.

TimezoneValue

Enums

BindingDataValue

Response row for spec data: type, plan metadata, and committed binding from overlay or spec literal.

ConversionTraceRole

DataValue

Parse-time data value (before type resolution)

DataValueInput

Typed data value from a client (CLI/WASM). JSON parsing stays outside [parse_data_value].

DateGranularity

Error

Error types for the Lemma system with source location tracking

ErrorKind

Classification of an Error. Serialized as the kind field on the flat object returned to JavaScript from WASM (engine/src/wasm.rs, JsError).

ExplanationNode

OperationResult

Result of an operation (evaluating a rule or expression) TODO: Rename. This can also represent a data value.

RegistryErrorKind

The kind of failure that occurred during a Registry operation.

RequestErrorKind

Distinguishes HTTP 404 (not found) from 400 (bad request) for request errors.

SourceType

TokenKind

TypeSpecification

ValueKind

Value payload (shape of a literal). No type attached. Measure unit is required; Ratio unit is optional (see plan ratio-units-optional.md).

VetoType

Why an operation yielded no value (domain veto).

Constants

EMBEDDED_STDLIB_REPOSITORY

Repository name reserved for the embedded standard library (repo lemma, spec units). User Engine::load must not target this name via SourceType::Dependency.

MAX_DATA_NAME_LENGTH

MAX_RULE_NAME_LENGTH

MAX_SPEC_NAME_LENGTH

UNITS_LEMMA

Traits

Registry

Trait for resolving external repository references.

Functions

format_explanation

format_parse_result

Format a ParseResult (repository groups + specs) into canonical Lemma source.

format_source

Parse a source string and format it to canonical Lemma source.

format_specs

Format a sequence of parsed specs into canonical Lemma source.

parse

parse_spec_set_id

Validate and normalize a spec set identifier (a workspace spec name).

resolve_effective

Resolve an optional effective datetime string for planning or evaluation.

resolve_registry_references

Resolve every uses reference that carries a registry repository qualifier in the loaded specs.

try_parse_type_constraint_command

Parses a constraint command name. Returns None for unknown (parser returns error).

type_detail_lines

Produce a human-readable summary of type constraints, or None when there are no constraints worth showing (e.g. bare boolean). Returns one formatted string per constraint or property of the type specification. Uses display_str for all rational bounds so they render as decimals, not as raw fractions.