Repository navigation
Deno source-to-source host→guest callback ABI (blocks withProgress/registerCommand/onDidSave) #199
Description
Problem
The Deno/Node source-to-source backend (lib/codegen_deno.ml) has no host→guest callback mechanism. It explicitly has "no handle table" (codegen_deno.ml:9) and ExprHandle lowering ignores handlers. The only working callback path in the estate is the wasm adapter packages/affine-vscode/mod.js, which resolves a handler Int via inst.exports.__indirect_function_table (wrapHandler).
Consequently, on the Deno source-to-source target, any extern that takes an AffineScript thunk the host must invoke is unimplementable:
vscode.window.withProgress(opts, work_thunk)— Async-extern ABI: bind withProgress + LanguageClient.sendRequest #103commands.registerCommand(name, handler)—stdlib/Vscode.affineworkspace.onDidSaveTextDocument(handler)—stdlib/Vscode.affine
These currently only function on the wasm backend.
Why separate from #103
#103 (async-extern ABI) split into:
- sendRequest — pure data-in → Thenable-out, no callback: shipped on the Deno path (PR-4, Refs Async-extern ABI: bind withProgress + LanguageClient.sendRequest #103).
- withProgress — requires this callback ABI.
The callback ABI is a distinct, larger, one-way-door design (it dictates how every host→guest callback is shaped on the source-to-source backend, not just async), so it is tracked here rather than expanding #103.
Design space (not yet decided)
- Guest exports a thunk-dispatch entrypoint;
codegen_denoemits a JS-side handle registry the adapter calls back into. - Alternatively: closures-as-values lowering so handlers are real JS functions passed directly (no Int handle indirection on the source-to-source path at all).
Acceptance
-
registerCommand,onDidSaveTextDocument,withProgressall functional on--deno-esm/--vscode-extensionoutput. - rsr-certifier vscode pilot fully restored (the
withProgress-wrapped checks).
Refs #103
Activity
feat(affine-vscode): languageClientSendRequest host binding (Refs #103)…
hyperpolymath commentedon May 18, 2026
Decisive finding — ABI shape resolved without a compiler change
Investigation of the chosen function-value ABI: a function-typed extern param typechecks today — provided the handler takes an explicit argument:
extern fn onSave(handler: fn(Int) -> Int)+onSave(fn(x: Int) => x)→ ✅ typechecksextern fn onCmd(handler: fn(Unit) -> Int)+onCmd(fn(u: Unit) => 0)→ ✅ typechecksextern fn onCmd(handler: fn() -> Int)+onCmd(fn() => 0)→ ❌TypeMismatch((Unit -> Int), Int)Root cause: AffineScript has a deliberate convention (
lib/typecheck.ml:752, mirrored inExprLambdasynth at ~742) that a zero-parameter function is typed as its bare return type, notUnit -> T. But the type syntaxfn() -> Tlowers toTArrow(Unit, _, T, _). So zero-arg lambda values and thefn() -> Ttype don't unify. Changing that convention is a language-wide one-way door (it governs every zero-arg call site) and is out of scope here.Resolution (no compiler change)
Handler bindings use an explicit
Unitparam:handler: fn(Unit) -> R; consumers writefn(_u: Unit) => { ... }. Slightly more ceremony thanfn(), but it is the honest, zero-risk realisation of the function-value ABI — the zero-arg-fn convention stays intact.Scope (consumers to migrate at root)
stdlib/Vscode.affine:registerCommand,onDidSaveTextDocument(+withProgressNotificationwork param from feat(stdlib): async-extern binding surface — Thenable + withProgress/sendRequest (Refs #103) #198) →fn(Unit) -> R.examples/vscode_extension_minimal.affine:registerCommand("…", 0)→ lambda.editors/vscode/src/extension.affine: real 5-command extension using a numbered-handler-dispatch idiom (handlers 0–4) — behaviour-preserving rewrite to passed function values.Tracked as PR-5a (binding + example + editors extension, 253-gated), PR-5b Deno lowering, PR-5c wasm marshalling, PR-5d rsr-certifier pilot.
Refs #199
feat(vscode): function-value callback ABI — registerCommand/onDidSave…
fix(affine-vscode): marshal closure-pointer handlers, not table indic…
feat(thenable): wasm-path thenable-resolution primitives (Closes #205) (
hyperpolymath commentedon May 18, 2026
Closing — host->guest callback ABI complete (STAGE-B).
The function-value callback ABI is shipped on
main:This unblocked withProgress / registerCommand / onDidSave. The rsr-certifier pilot that would have demonstrated it in a real consumer (was PR-5d-B) is decoupled to an independent standards-repo follow-up and no longer gates this issue.
Closed on owner approval (joint close, 2026-05-18).
feat(stdlib): add httpPostJson async-extern for out-of-process JSON P…
feat(stdlib): add jsonField extern for minimal JSON field extraction (#…
feat(rsr-certifier): BoJ-first 3-tier compliance in the VS Code exten…
feat(affine-vscode): implement withProgressNotification runtime adapt…
feat: #225 typed-wasm Http — ADR-013 + PR1 verified Thenable foundati…
feat(codegen): #225 PR2 — WasmGC CPS transform, Async base case (ADR-013
feat(codegen): #225 PR3a — WasmGC CPS transform, multi-var live-local…
feat(http): #225 PR3d — typed Response reader (ADR-013 §value-reconst…
docs(http): #225 PR4 — joint-close #160 + #225 (ADR-013 delivery comp…
docs(http): #225 PR4 — joint-close #160 + #225 (ADR-013 delivery comp…
feat(codegen): #234 S3 — effect-threaded async-boundary detection (AD…
test(codegen): #235 — engine-validate the #199 closure ABI independen…
feat(wasi): #180 ADR-015 S4a — clock_now_ms builtin (preview1 → wasi:…
feat(wasi): #180 ADR-015 S4b — env_count/arg_count + multi-import ind…