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perf: back say and Http.Status.set with EffectFn1 foreigns - #8
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The curried String -> Effect Unit FFI shape compiles every call into
two Lua calls plus a fresh effect-thunk closure. Declaring the foreigns
as EffectFn1 (sayImpl, setImpl) behind thin public wrappers keeps the
API unchanged while letting the compiler collapse saturated call sites
into one direct call: M.say("x")() becomes sayImpl("x"). Demonstrated
by a differential link of a probe app against this branch vs main.
Refs purescript-lua/purescript-lua#186.
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Problem
say :: String -> Effect UnitandLua.Ngx.Http.Status.set :: Status -> Effect Unitwere curried effect foreigns, so every call paid two Lua calls plus a freshly allocated effect thunk. With the compiler's uncurried lift in place (purescript-lua/purescript-lua#198), anEffectFn1shape compiles to a single direct call instead. These are exactly the Lua-specific foreigns the #186 audit scoped for conversion (ngx has no upstream to stay API-compatible with, and the public API does not change anyway).Change
The foreigns become
sayImpl/setImpl :: EffectFn1 …with thin public wrappers (say = runEffectFn1 sayImpl), and the.luaentries become 1-ary functions performing the effect directly.get :: Effect Statusstays as is: a thunk is already a single call, and there is noEffectFn0. Status constants untouched.Verification
scripts/buildgreen. Differential link of a probe app (say "hello" *> say "world" *> set ok) againstmainvs this branch: every call site collapses fromLua_Ngx_say("hello")()(two calls and a closure per invocation) toLua_Ngx_sayImpl("hello"), one direct call with the effect thunk fused away by magic-do. Both linked outputs were executed under Lua 5.1 with anngxstub and produce identical behaviour (same say output, same status assignment). No OpenResty runtime smoke: the change surface is the calling convention only.Suggested release: minor (v0.3.0, since the module surface gains the
*Implexports) plus a package-set bump.Refs purescript-lua/purescript-lua#186.