Enum FixpointError 

pub enum FixpointError {
    RuleNotForTarget {
        rule_index: usize,
        observed: String,
        expected: String,
    },
    HeadArityMismatch {
        rule_index: usize,
        observed_arity: usize,
        expected_arity: usize,
    },
    TargetPredicateInBaseRelations {
        name: String,
    },
    RuleEval {
        rule_index: usize,
        source: RefEvalError,
    },
    MaxIterationsExceeded {
        limit: usize,
        observed_size: usize,
    },
    TargetSchemaIndeterminable,
    InvalidMaxIterations,
}

Errors surfaced by evaluate_fixpoint.

Variants

RuleNotForTarget

A rule’s head predicate did not equal target_predicate. The fixpoint evaluator only accepts rules that contribute to the named target.

Fields

rule_index: usize

Index of the offending rule in the input slice.

observed: String

Head predicate observed.

expected: String

Expected target predicate.

HeadArityMismatch

Two rules disagreed on the target predicate’s head arity. Surfaced separately from the per-row arity check so the caller sees the rule-level shape mismatch directly rather than as a downstream RelationRowArityMismatch.

Fields

rule_index: usize

Index of the offending rule in the input slice.

observed_arity: usize

Head arity observed on this rule.

expected_arity: usize

Head arity established by the first non-empty-head rule.

TargetPredicateInBaseRelations

target_predicate was already present in base_relations. The fixpoint constructs the target relation; allowing base_relations to seed it would silently shadow the caller’s seed on the first iteration. If you want a seed, encode it as a base-case rule.

Fields

name: String

The target predicate name as supplied.

RuleEval

A rule failed evaluation. Wraps the per-rule error from evaluate_rule with the rule’s index in the input slice for diagnostic precision.

Fields

rule_index: usize

Index in the input slice.

source: RefEvalError

The wrapped per-rule error.

MaxIterationsExceeded

The fixpoint did not converge within FixpointConfig::max_iterations.

Fields

limit: usize

The configured cap.

observed_size: usize

Size of the derived target relation at the cap.

TargetSchemaIndeterminable

No supplied rule produced a head whose arity could be inferred — caller supplied an empty rules slice or every rule had an empty head.

InvalidMaxIterations

max_iterations was zero. Must be ≥ 1.

Trait Implementations

impl Clone for FixpointError

fn clone(&self) -> FixpointError

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for FixpointError

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

Formats the value using the given formatter.

impl PartialEq for FixpointError

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

Tests for self and other values to be equal, and is used by ==.

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

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl StructuralPartialEq for FixpointError