giles 86ddaf255c go: types.sx — literal synth + binop + assignability; canonical pitfall handled + 16 tests [shapes-static-types-bidirectional] ...

Phase 3 cont. Adds:

  * go-classify-literal-string — heuristic detection of literal kind
    from the value-string (parser strips lexer's kind tag; flagged for
    follow-up to extend AST shape).
  * go-synth-literal — :ty-untyped-int / -float / -imag / -string.
  * go-synth-binop — arithmetic, bitwise, comparison, logical ops with
    untyped-constant unification:
      untyped-int + untyped-float → untyped-float
      untyped + typed              → typed
      comparison ops               → bool
      logical ops                  → bool
  * go-untyped? + go-type-assignable? — pluggable assignability that
    swaps in where structural equality used to gate go-check. Untyped
    int assignable to any numeric type; untyped float assignable to
    float/complex; untyped string to string.

**Canonical Go pitfall handled correctly**: `var x float64 = 42 / 7`
parses to a binop, synth produces :ty-untyped-int (since BOTH operands
are untyped, the int division stays in the int domain), and check
against float64 returns :ok via assignability. Wrong implementations
that float-coerce eagerly would give 6.0; the right behaviour is
"compute 6 as int, then convert to float64 = 6.0".

Verified by test "binop: 42 / 7 assignable to float64 (canonical
pitfall)" and the type-only test "binop: 42 / 7 — untyped int".

Sister-plan static-types-bidirectional diary updated with the
**pluggable-assignable-predicate** kit-API proposal:

  (check-with assignable? CTX EXPR EXPECTED)

Each consumer plugs in its own variance discipline (Go untyped-flow,
TS structural subtyping, Rust lifetime-aware identity) without
rewriting synth or the judgment skeleton.

types 28/28, total 333/333.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

2026-05-27 20:46:03 +00:00

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