From 40c0f1e0634a9aae815f3c6ac7b802ba49559e1d Mon Sep 17 00:00:00 2001
From: Yura Lazarev <unisay@gmail.com>
Date: Mon, 13 Jul 2026 15:30:07 +0200
Subject: [PATCH] perf: back say and Http.Status.set with EffectFn1 foreigns

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.
---
 changelog.d/20260713_153000_effectfn_ffi.md | 7 +++++++
 src/Lua/Ngx.lua                             | 2 +-
 src/Lua/Ngx.purs                            | 5 ++++-
 src/Lua/Ngx/Http/Status.lua                 | 2 +-
 src/Lua/Ngx/Http/Status.purs                | 7 ++++++-
 5 files changed, 19 insertions(+), 4 deletions(-)
 create mode 100644 changelog.d/20260713_153000_effectfn_ffi.md

diff --git a/changelog.d/20260713_153000_effectfn_ffi.md b/changelog.d/20260713_153000_effectfn_ffi.md
new file mode 100644
index 0000000..a802837
--- /dev/null
+++ b/changelog.d/20260713_153000_effectfn_ffi.md
@@ -0,0 +1,7 @@
+### Changed
+
+- `say` and `Lua.Ngx.Http.Status.set` are backed by `EffectFn1` foreigns
+  (`sayImpl`, `setImpl`) behind thin public wrappers; the public API is
+  unchanged. A saturated `say s` / `set st` in compiled code is now a single
+  direct Lua call with no per-call thunk allocation (previously two calls
+  and a fresh closure per invocation).
diff --git a/src/Lua/Ngx.lua b/src/Lua/Ngx.lua
index 1c62c1d..88b9ae3 100644
--- a/src/Lua/Ngx.lua
+++ b/src/Lua/Ngx.lua
@@ -1 +1 @@
-return {say = (function(msg) return function() ngx.say(msg) end end)}
+return {sayImpl = (function(msg) ngx.say(msg) end)}
diff --git a/src/Lua/Ngx.purs b/src/Lua/Ngx.purs
index 8cc8acc..d2804ba 100644
--- a/src/Lua/Ngx.purs
+++ b/src/Lua/Ngx.purs
@@ -2,6 +2,9 @@ module Lua.Ngx where
 
 import Data.Unit (Unit)
 import Effect (Effect)
+import Effect.Uncurried (EffectFn1, runEffectFn1)
 
-foreign import say :: String -> Effect Unit
+foreign import sayImpl :: EffectFn1 String Unit
 
+say :: String -> Effect Unit
+say = runEffectFn1 sayImpl
diff --git a/src/Lua/Ngx/Http/Status.lua b/src/Lua/Ngx/Http/Status.lua
index c4f4164..4ddafff 100644
--- a/src/Lua/Ngx/Http/Status.lua
+++ b/src/Lua/Ngx/Http/Status.lua
@@ -36,5 +36,5 @@ return {
   versionNotSupported = (ngx.HTTP_VERSION_NOT_SUPPORTED),
   insufficientStorage = (ngx.HTTP_INSUFFICIENT_STORAGE),
   get = (function() return ngx.status end),
-  set = (function(status) return function() ngx.status = status end end)
+  setImpl = (function(status) ngx.status = status end)
 }
diff --git a/src/Lua/Ngx/Http/Status.purs b/src/Lua/Ngx/Http/Status.purs
index da349d7..a5fcb7e 100644
--- a/src/Lua/Ngx/Http/Status.purs
+++ b/src/Lua/Ngx/Http/Status.purs
@@ -2,6 +2,7 @@ module Lua.Ngx.Http.Status where
 
 import Data.Unit (Unit)
 import Effect (Effect)
+import Effect.Uncurried (EffectFn1, runEffectFn1)
 
 foreign import data Status :: Type
 
@@ -42,5 +43,9 @@ foreign import gatewayTimeout :: Status
 foreign import versionNotSupported :: Status
 foreign import insufficientStorage :: Status
 
-foreign import set :: Status -> Effect Unit
+foreign import setImpl :: EffectFn1 Status Unit
+
+set :: Status -> Effect Unit
+set = runEffectFn1 setImpl
+
 foreign import get :: Effect Status