iter 22-tidy.6: journal entry, milestone-22 carried debt empty

2026-05-10 05:01:39 +02:00
parent 51011511b4
commit 14b3dc4a63
1 changed files with 93 additions and 0 deletions
@@ -12272,3 +12272,96 @@ Carried-debt status (after this iter):
 - ✅ Lib.rs gap-related sites at lib.rs:1266 / 1853-1856 / 1978 /
  2314-2316 — audit confirmed defensive (no action needed; see
  `2026-05-10 — Audit: mono-pass env-seeding gaps`).
+
+## 2026-05-10 — Iteration 22-tidy.6: Form-B prose printer arms for ClassDef + InstanceDef
+
+Closing the third (and final gating) milestone-22 carried-debt
+item: `crates/ailang-prose` previously rendered `Def::Class` /
+`Def::Instance` as a one-line placeholder
+(`// (class Foo a) -- full Form-B projection deferred (post-22)`).
+This iteration replaces the placeholder with a full Rust-flavoured
+projection covering class header, optional `extends <SuperClass>`,
+methods (signature plus optional `default { ... }` body), and
+instance header + method bodies.
+
+`write_fn_def` was extended in the same iter to render forall
+class constraints (`forall<a> where Ord a`) so a class-constrained
+fn signature survives the projection without semantic loss — a
+prerequisite for the superclass snapshot to be useful.
+
+Three new snapshot fixtures pin every branch of the new render:
+
+- `examples/test_22b3_default_e2e.prose.txt` — class-with-default +
+  instance-with-no-method-overrides (no superclass, default Some).
+- `examples/test_22b2_instance_present.prose.txt` — class-with-abstract
+  method + instance-with-method-override (default None, instance
+  methods non-empty).
+- `examples/test_22b2_constraint_declared_via_superclass.prose.txt`
+  — class-with-superclass + class-constrained fn (extends Some,
+  forall constraints non-empty).
+
+Tasks (commit subjects):
+
+- 22-tidy.6.1: write_class_def + write_instance_def — full Form-B projection
+- 22-tidy.6.1 fixup: cover abstract-method + instance-override branches; doc + fallback comments
+- 22-tidy.6.2: write_fn_def renders forall class constraints
+
+Acceptance: 3 RED-first snapshot tests then GREEN; full workspace
+test sweep green; bench gates 0/0/0; the four pre-existing prose
+snapshots (rc_own_param_drop, rc_match_arm_partial_drop_leak,
+rc_app_let_partial_drop_leak, bench_list_sum) stay green
+(unaffected — none contain class/instance). The placeholder text
+and comment are gone from `crates/ailang-prose/src/lib.rs`
+(grep confirms zero hits for "full Form-B projection deferred").
+
+Mid-iter design notes:
+
+- Class methods render with synthesised parameter slot names
+  (`x`, `x1`, `x2`, ...) because the AST stores method types
+  but no parameter names. Inline comment in `write_class_method`
+  records the rationale.
+- Class-method `default` bodies render as their underlying AST
+  shape, which in practice is `Term::Lam` (the parser wraps the
+  surface `default` body as a closure). So `default { |x: a| -> Int
+  { 99 } }` is the faithful render — the closure form is the AST,
+  not the renderer wrapping it.
+- Instance methods render as `fn <name> { <body> }` without a
+  signature. The signature is recoverable from the class
+  declaration via `InstanceDef.class` lookup
+  (typecheck-context-dependent substitution of `class.method.ty`
+  with `class.param -> instance.type_`). Per the prose policy
+  ("deliberately lossy where the LLM can re-derive the dropped
+  machinery from typecheck context"), this is the correct
+  projection — the class def is the authoritative signature
+  source.
+- Plan's Step 4 prescribed adding `Constraint` to the
+  `use ailang_core::ast::{...}` line, but field access through
+  `c.class` / `&c.type_` does not require naming the type;
+  implementer correctly omitted the import to avoid an
+  `unused_imports` warning.
+
+Carried-debt status (after this iter, milestone 22 fully closed):
+
+- ✅ Primitive-name-set consolidation (closed 22-tidy.4).
+- ✅ Strict duplicate-clause detection in fn/const/data
+  (closed 22-tidy.5).
+- ✅ Form-B (prose) printer arms for ClassDef / InstanceDef
+  (closed this iter).
+- ✅ Lib.rs gap-related sites at lib.rs:1266 / 1853-1856 / 1978 /
+  2314-2316 — audit confirmed defensive (no action needed).
+
+Milestone 22 carried debt is now empty. Next milestone targets
+(orchestrator's call): post-22 Prelude (gated on user-author
+demand for primitive `Show`/`Eq`/`Ord`), operator routing through
+`Eq`/`Ord` (gated on bench re-baselining), or the
+`types/ctor_index` overlay shape question queued from
+`2026-05-10 — Audit close: env-construction unify`.
+
+Out-of-scope observation (not new debt — quality-review nit
+surfaced during Task 2): `write_type`'s `Type::Forall` arm
+still silently drops constraints in inline-type rendering
+(`crates/ailang-prose/src/lib.rs` `write_type` Type::Forall arm).
+The inline path is unreachable for the surface forms emitted by
+the parser today (forall only appears at fn-signature top level),
+so the gap is dormant. If a future feature carries a forall in
+inline position with constraints, this is the place to extend.