0.2.3-understand-du_tag

understand-du_tag

CALL NUMBER: deep_tagged_union_type.du_tag DEFINITION: A value-level or type-level label that uniquely identifies which variant of a discriminated union is active in a given value. The tag is the first-class evidence of variant membership.

Invoke this skill to understand du_tag down to its primitives. The RELATIVE ROOT below is the least-fixed-point closure of everything it bundles from — the full import cone, grouped by the lib each prim comes from. Projected from a prover-typed KB (MAP/SWI-Prolog consistency gate): every reference below resolves.

THE RELATIVE ROOT (the import cone, by lib)

from deep_tagged_union_type

• du_payload (d1): The data value carried by a specific variant of a discriminated union. Only one payload is live at a time; the tag selects which one.

CONSUMERS (what needs this)

du_closed, du_match, du_open, du_variant, prism_builder, prism_matcher

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Projected from the type systems for working programmers KB (242 concepts / 186 relations) — consistency-typed by MAP; the facet list after the colon IS the cross-lib dependency web.

(leaf — this is an actual skill.)