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extern type / extern fn declarations not parseable in user source #42
Description
Activity
Investigated, deferring
I considered taking this on as a follow-up to PR #67 (which adds
[T]array syntax). After reading the lexer + parser + AST, the change is multi-piece:- Lexer: add
("extern", EXTERN)to the keyword table — trivial. - Parser: add
EXTERNtoken decl + rules forextern fnandextern type— moderate. - AST: requires either new constructors (ExternFnDecl, ExternTypeDecl) or a 'no-body' flag on the existing fn_decl/type_decl — this is the sticking point.
- Typechecker: needs to treat extern declarations as opaque foreign references whose types are taken on faith.
- Codegen: needs to emit wasm imports against the extern declarations.
(3) cascades through the rest of the compiler. Without local build verification (which would be ~1-2 hours of dune iteration to get right), the risk of getting (3) and downstream wrong is high.
I've separately filed #73 for a different codegen issue I encountered while validating PR #67, and a comment on PR #67 showing the [T] fix is locally verified. For #42 I'd recommend the maintainer takes it — the multi-piece change benefits from the review-and-iterate cycle that requires an OCaml dev environment.
Cross-reference: this issue is the connector-layer counterpart to the extern shape used by
affinescript-pixijs's ownpixi.as, so blocking on it is blocking on the entire Pixi connector. Effort vs leverage is favourable for the maintainer to take on directly.- Lexer: add
- added a commit that references this issue
on May 3, 2026 - added a commit that references this issue
on May 11, 2026 - added a commit that references this issue
on May 11, 2026
Surfaced by: IDApTIK migration /
affinescript-pixijsintegration attempt (2026-05-02)Affected version: v0.1.0
Severity: Blocking for
@affinescript/pixijsand any other connector package that uses FFI-style imports. The package's ownsrc/pixi.ascannot be compiled by today's toolchain.Reproducer
The shape used by
affinescript/affinescript-pixijs/src/pixi.as:externis rejected at the very first character — it's not a recognised keyword in the user-source grammar.Why this matters
affinescript-pixijs/src/pixi.as(the canonical PixiJS connector) is structured aroundextern type Application/extern fn createApplication(...)declarations whose implementations are intended to be linked at runtime via "Typed WASM imports" (per the file's header comment). Withoutexternparsing, the connector itself cannot be compiled, which means any consumer of@affinescript/pixijsis blocked.For IDApTIK specifically, this gates the entire screen-and-rendering side of the migration (Wave 3 popups, screens, UI primitives) because they all need to call into PixiJS.
Cross-reference
externis the structural mechanism; effect handlers are the runtime mechanism.@affinescript/pixijs,@affinescript/dom, and any future@affinescript/*package that uses FFI imports.externis intentionally being held back pending a final design, document the interim shape (e.g.@moduleannotations? hand-written wasm imports table?) so connector authors know what to write.