Module filter 

Input filters: idempotent, per-cell domain constraints.

A Filter conforms or rejects a value written externally to its cell, applied live by crate::sheet::Sheet::propagate against a source cell’s own current value (see crate::sheet::Sheet::add_filter), and is separately re-evaluated as a non-gating diagnostic against a value a relationship’s method derives for that cell (also in crate::sheet::Sheet::propagate).

Structs

Filter

An idempotent, per-cell domain constraint with optional dynamic arguments.

Enums

FilterKind

What shape of validation/derivation a Filter performs, beyond its opaque function — set by adam-lang’s compile phase when a filter’s expression matches a recognized structural form. Opaque carries no extra information; consumers that don’t care about structure treat every kind identically at write/propagate time — FilterKind is purely informational, queried by consumers like begin’s UI that want to render a specialized editor without inspecting the filter’s function.

FilterViolation

The outcome of re-checking a filter against a value a relationship’s method derived, rather than a value written externally.