allow accessing args in Effect.fn pipe (#4417)

Co-authored-by: Michael Arnaldi <[email protected]>
Effect-TS · Feb 11, 2025 · b2b17d6 · b2b17d6
1 parent 04e1a4e
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diff --git a/.changeset/mighty-turtles-battle.md b/.changeset/mighty-turtles-battle.md
@@ -0,0 +1,5 @@
+---
+"effect": minor
+---
+
+allow accessing args in Effect.fn pipe
diff --git a/packages/effect/src/Effect.ts b/packages/effect/src/Effect.ts
@@ -13567,7 +13567,8 @@ export namespace fn {
           AEff,
           [Eff] extends [never] ? never : [Eff] extends [YieldWrap<Effect<infer _A, infer E, infer _R>>] ? E : never,
           [Eff] extends [never] ? never : [Eff] extends [YieldWrap<Effect<infer _A, infer _E, infer R>>] ? R : never
-        >
+        >,
+        ...args: Args
       ) => A
     ): (...args: Args) => A
     <Eff extends YieldWrap<Effect<any, any, any>>, AEff, Args extends Array<any>, A, B extends Effect<any, any, any>>(
@@ -13577,9 +13578,10 @@ export namespace fn {
           AEff,
           [Eff] extends [never] ? never : [Eff] extends [YieldWrap<Effect<infer _A, infer E, infer _R>>] ? E : never,
           [Eff] extends [never] ? never : [Eff] extends [YieldWrap<Effect<infer _A, infer _E, infer R>>] ? R : never
-        >
+        >,
+        ...args: Args
       ) => A,
-      b: (_: A) => B
+      b: (_: A, ...args: Args) => B
     ): (...args: Args) => B
     <
       Eff extends YieldWrap<Effect<any, any, any>>,
@@ -13595,10 +13597,11 @@ export namespace fn {
           AEff,
           [Eff] extends [never] ? never : [Eff] extends [YieldWrap<Effect<infer _A, infer E, infer _R>>] ? E : never,
           [Eff] extends [never] ? never : [Eff] extends [YieldWrap<Effect<infer _A, infer _E, infer R>>] ? R : never
-        >
+        >,
+        ...args: Args
       ) => A,
-      b: (_: A) => B,
-      c: (_: B) => C
+      b: (_: A, ...args: Args) => B,
+      c: (_: B, ...args: Args) => C
     ): (...args: Args) => C
     <
       Eff extends YieldWrap<Effect<any, any, any>>,
@@ -13615,11 +13618,12 @@ export namespace fn {
           AEff,
           [Eff] extends [never] ? never : [Eff] extends [YieldWrap<Effect<infer _A, infer E, infer _R>>] ? E : never,
           [Eff] extends [never] ? never : [Eff] extends [YieldWrap<Effect<infer _A, infer _E, infer R>>] ? R : never
-        >
+        >,
+        ...args: Args
       ) => A,
-      b: (_: A) => B,
-      c: (_: B) => C,
-      d: (_: C) => D
+      b: (_: A, ...args: Args) => B,
+      c: (_: B, ...args: Args) => C,
+      d: (_: C, ...args: Args) => D
     ): (...args: Args) => D
     <
       Eff extends YieldWrap<Effect<any, any, any>>,
@@ -13637,12 +13641,13 @@ export namespace fn {
           AEff,
           [Eff] extends [never] ? never : [Eff] extends [YieldWrap<Effect<infer _A, infer E, infer _R>>] ? E : never,
           [Eff] extends [never] ? never : [Eff] extends [YieldWrap<Effect<infer _A, infer _E, infer R>>] ? R : never
-        >
+        >,
+        ...args: Args
       ) => A,
-      b: (_: A) => B,
-      c: (_: B) => C,
-      d: (_: C) => D,
-      e: (_: D) => E
+      b: (_: A, ...args: Args) => B,
+      c: (_: B, ...args: Args) => C,
+      d: (_: C, ...args: Args) => D,
+      e: (_: D, ...args: Args) => E
     ): (...args: Args) => E
     <
       Eff extends YieldWrap<Effect<any, any, any>>,
@@ -13661,13 +13666,14 @@ export namespace fn {
           AEff,
           [Eff] extends [never] ? never : [Eff] extends [YieldWrap<Effect<infer _A, infer E, infer _R>>] ? E : never,
           [Eff] extends [never] ? never : [Eff] extends [YieldWrap<Effect<infer _A, infer _E, infer R>>] ? R : never
-        >
+        >,
+        ...args: Args
       ) => A,
-      b: (_: A) => B,
-      c: (_: B) => C,
-      d: (_: C) => D,
-      e: (_: D) => E,
-      f: (_: E) => F
+      b: (_: A, ...args: Args) => B,
+      c: (_: B, ...args: Args) => C,
+      d: (_: C, ...args: Args) => D,
+      e: (_: D, ...args: Args) => E,
+      f: (_: E, ...args: Args) => F
     ): (...args: Args) => F
     <
       Eff extends YieldWrap<Effect<any, any, any>>,
@@ -13687,14 +13693,15 @@ export namespace fn {
           AEff,
           [Eff] extends [never] ? never : [Eff] extends [YieldWrap<Effect<infer _A, infer E, infer _R>>] ? E : never,
           [Eff] extends [never] ? never : [Eff] extends [YieldWrap<Effect<infer _A, infer _E, infer R>>] ? R : never
-        >
+        >,
+        ...args: Args
       ) => A,
-      b: (_: A) => B,
-      c: (_: B) => C,
-      d: (_: C) => D,
-      e: (_: D) => E,
-      f: (_: E) => F,
-      g: (_: F) => G
+      b: (_: A, ...args: Args) => B,
+      c: (_: B, ...args: Args) => C,
+      d: (_: C, ...args: Args) => D,
+      e: (_: D, ...args: Args) => E,
+      f: (_: E, ...args: Args) => F,
+      g: (_: F, ...args: Args) => G
     ): (...args: Args) => G
     <
       Eff extends YieldWrap<Effect<any, any, any>>,
@@ -13715,15 +13722,16 @@ export namespace fn {
           AEff,
           [Eff] extends [never] ? never : [Eff] extends [YieldWrap<Effect<infer _A, infer E, infer _R>>] ? E : never,
           [Eff] extends [never] ? never : [Eff] extends [YieldWrap<Effect<infer _A, infer _E, infer R>>] ? R : never
-        >
+        >,
+        ...args: Args
       ) => A,
-      b: (_: A) => B,
-      c: (_: B) => C,
-      d: (_: C) => D,
-      e: (_: D) => E,
-      f: (_: E) => F,
-      g: (_: F) => G,
-      h: (_: G) => H
+      b: (_: A, ...args: Args) => B,
+      c: (_: B, ...args: Args) => C,
+      d: (_: C, ...args: Args) => D,
+      e: (_: D, ...args: Args) => E,
+      f: (_: E, ...args: Args) => F,
+      g: (_: F, ...args: Args) => G,
+      h: (_: G, ...args: Args) => H
     ): (...args: Args) => H
     <
       Eff extends YieldWrap<Effect<any, any, any>>,
@@ -13745,16 +13753,17 @@ export namespace fn {
           AEff,
           [Eff] extends [never] ? never : [Eff] extends [YieldWrap<Effect<infer _A, infer E, infer _R>>] ? E : never,
           [Eff] extends [never] ? never : [Eff] extends [YieldWrap<Effect<infer _A, infer _E, infer R>>] ? R : never
-        >
+        >,
+        ...args: Args
       ) => A,
-      b: (_: A) => B,
-      c: (_: B) => C,
-      d: (_: C) => D,
-      e: (_: D) => E,
-      f: (_: E) => F,
-      g: (_: F) => G,
-      h: (_: G) => H,
-      i: (_: H) => I
+      b: (_: A, ...args: Args) => B,
+      c: (_: B, ...args: Args) => C,
+      d: (_: C, ...args: Args) => D,
+      e: (_: D, ...args: Args) => E,
+      f: (_: E, ...args: Args) => F,
+      g: (_: F, ...args: Args) => G,
+      h: (_: G, ...args: Args) => H,
+      i: (_: H, ...args: Args) => I
     ): (...args: Args) => I
   }
 
@@ -13768,75 +13777,75 @@ export namespace fn {
     ): (...args: Args) => Eff
     <Eff extends Effect<any, any, any>, A, Args extends Array<any>>(
       body: (...args: Args) => A,
-      a: (_: A) => Eff
+      a: (_: A, ...args: Args) => Eff
     ): (...args: Args) => Eff
     <Eff extends Effect<any, any, any>, A, B, Args extends Array<any>>(
       body: (...args: Args) => A,
-      a: (_: A) => B,
-      b: (_: B) => Eff
+      a: (_: A, ...args: Args) => B,
+      b: (_: B, ...args: Args) => Eff
     ): (...args: Args) => Eff
     <Eff extends Effect<any, any, any>, A, B, C, Args extends Array<any>>(
       body: (...args: Args) => A,
-      a: (_: A) => B,
-      b: (_: B) => C,
-      c: (_: C) => Eff
+      a: (_: A, ...args: Args) => B,
+      b: (_: B, ...args: Args) => C,
+      c: (_: C, ...args: Args) => Eff
     ): (...args: Args) => Eff
     <Eff extends Effect<any, any, any>, A, B, C, D, Args extends Array<any>>(
       body: (...args: Args) => A,
-      a: (_: A) => B,
-      b: (_: B) => C,
-      c: (_: C) => D,
-      d: (_: D) => Eff
+      a: (_: A, ...args: Args) => B,
+      b: (_: B, ...args: Args) => C,
+      c: (_: C, ...args: Args) => D,
+      d: (_: D, ...args: Args) => Eff
     ): (...args: Args) => Eff
     <Eff extends Effect<any, any, any>, A, B, C, D, E, Args extends Array<any>>(
       body: (...args: Args) => A,
-      a: (_: A) => B,
-      b: (_: B) => C,
-      c: (_: C) => D,
-      d: (_: D) => E,
-      e: (_: E) => Eff
+      a: (_: A, ...args: Args) => B,
+      b: (_: B, ...args: Args) => C,
+      c: (_: C, ...args: Args) => D,
+      d: (_: D, ...args: Args) => E,
+      e: (_: E, ...args: Args) => Eff
     ): (...args: Args) => Eff
     <Eff extends Effect<any, any, any>, A, B, C, D, E, F, Args extends Array<any>>(
       body: (...args: Args) => A,
-      a: (_: A) => B,
-      b: (_: B) => C,
-      c: (_: C) => D,
-      d: (_: D) => E,
-      e: (_: E) => F,
-      f: (_: E) => Eff
+      a: (_: A, ...args: Args) => B,
+      b: (_: B, ...args: Args) => C,
+      c: (_: C, ...args: Args) => D,
+      d: (_: D, ...args: Args) => E,
+      e: (_: E, ...args: Args) => F,
+      f: (_: F, ...args: Args) => Eff
     ): (...args: Args) => Eff
     <Eff extends Effect<any, any, any>, A, B, C, D, E, F, G, Args extends Array<any>>(
       body: (...args: Args) => A,
-      a: (_: A) => B,
-      b: (_: B) => C,
-      c: (_: C) => D,
-      d: (_: D) => E,
-      e: (_: E) => F,
-      f: (_: E) => G,
-      g: (_: G) => Eff
+      a: (_: A, ...args: Args) => B,
+      b: (_: B, ...args: Args) => C,
+      c: (_: C, ...args: Args) => D,
+      d: (_: D, ...args: Args) => E,
+      e: (_: E, ...args: Args) => F,
+      f: (_: F, ...args: Args) => G,
+      g: (_: G, ...args: Args) => Eff
     ): (...args: Args) => Eff
     <Eff extends Effect<any, any, any>, A, B, C, D, E, F, G, H, Args extends Array<any>>(
       body: (...args: Args) => A,
-      a: (_: A) => B,
-      b: (_: B) => C,
-      c: (_: C) => D,
-      d: (_: D) => E,
-      e: (_: E) => F,
-      f: (_: E) => G,
-      g: (_: G) => H,
-      h: (_: H) => Eff
+      a: (_: A, ...args: Args) => B,
+      b: (_: B, ...args: Args) => C,
+      c: (_: C, ...args: Args) => D,
+      d: (_: D, ...args: Args) => E,
+      e: (_: E, ...args: Args) => F,
+      f: (_: F, ...args: Args) => G,
+      g: (_: G, ...args: Args) => H,
+      h: (_: H, ...args: Args) => Eff
     ): (...args: Args) => Eff
     <Eff extends Effect<any, any, any>, A, B, C, D, E, F, G, H, I, Args extends Array<any>>(
       body: (...args: Args) => A,
-      a: (_: A) => B,
-      b: (_: B) => C,
-      c: (_: C) => D,
-      d: (_: D) => E,
-      e: (_: E) => F,
-      f: (_: E) => G,
-      g: (_: G) => H,
-      h: (_: H) => I,
-      i: (_: H) => Eff
+      a: (_: A, ...args: Args) => B,
+      b: (_: B, ...args: Args) => C,
+      c: (_: C, ...args: Args) => D,
+      d: (_: D, ...args: Args) => E,
+      e: (_: E, ...args: Args) => F,
+      f: (_: F, ...args: Args) => G,
+      g: (_: G, ...args: Args) => H,
+      h: (_: H, ...args: Args) => I,
+      i: (_: H, ...args: Args) => Eff
     ): (...args: Args) => Eff
   }
 }
@@ -13994,7 +14003,7 @@ function fnApply(options: {
   if (options.pipeables.length > 0) {
     try {
       for (const x of options.pipeables) {
-        effect = x(effect)
+        effect = x(effect, ...options.args)
       }
     } catch (error) {
       effect = fnError

diff --git a/packages/effect/src/internal/core.ts b/packages/effect/src/internal/core.ts
@@ -1430,7 +1430,7 @@ export const fnUntraced: Effect.fn.Gen = (body: Function, ...pipeables: Array<an
     : function(this: any, ...args: Array<any>) {
       let effect = fromIterator(() => body.apply(this, args))
       for (const x of pipeables) {
-        effect = x(effect)
+        effect = x(effect, ...args)
       }
       return effect
     }

diff --git a/packages/effect/test/Effect/fn.test.ts b/packages/effect/test/Effect/fn.test.ts
@@ -1,6 +1,6 @@
 import { describe, it } from "@effect/vitest"
 import { Cause, Effect } from "effect"
-import { assertInstanceOf, assertTrue, strictEqual } from "effect/test/util"
+import { assertEquals, assertInstanceOf, assertTrue, strictEqual } from "effect/test/util"
 
 describe("Effect.fn", () => {
   it.effect("catches defects in the function", () =>
@@ -64,4 +64,17 @@ describe("Effect.fn", () => {
       assertInstanceOf(cause.right.defect, Error)
       strictEqual(cause.right.defect.message, "test2")
     }))
+
+  it.effect("can access args in single pipe", () =>
+    Effect.gen(function*() {
+      const fn = Effect.fn("test")(
+        function*(n: number) {
+          return n
+        },
+        (effect, n) => Effect.map(effect, (a) => a + n),
+        (effect, n) => Effect.map(effect, (a) => a + n)
+      )
+      const n = yield* fn(1)
+      assertEquals(n, 3)
+    }))
 })