Agent Skills: chalk-interner

What

The Chalk Interner pattern separates a type handle from its open form using a trait. Ty<I>(I::InternedTy) is the handle; TyKind<I> is the open enum with all variants. The Interner trait bridges them with intern_ty() and ty_data() — consumers only see Ty<I> and call .data(), never choosing the storage strategy. The embedder (rustc or tests) picks arena-interned integers, Box<TyKind>, or Arc.

Mapping to b00t: Ty<I> → Datum<S: DatumStore> handle, TyKind<I> → BootDatum, Interner → DatumStore trait, arena-interned → future irontology graph store, Box strategy → current HashMap<String, BootDatum> (eager), integer index → future SQLite rowid + lazy-load. A Chalk-style abstraction would let future stores be lazy (SQLite, Qdrant) without changing callers. The FOL/Horn clause connection: Chalk compiles Rust trait goals into Prolog-style Horn clauses; b00t's compile_datum_triples → graph_rules::derive → find_adjacent follows the same pattern.

When to Use

Use the Chalk Interner pattern when designing a trait-based abstraction layer over multiple storage backends. Load this skill when working on the DatumStore trait, adding SQLite/Qdrant backends, or understanding how b00t's triple graph relates to type theory.

How

1. Define a trait with associated types: InternedTy (opaque storage) and methods intern_ty() / ty_data().
2. Consumers use the handle type only — they never pick the storage strategy.
3. Implement the trait for each storage backend (eager HashMap, lazy SQLite, graph-based).
4. The abstraction ensures storage changes do not affect consumers.