return Exit values from Fiber.awaitAll (#3147)

Co-authored-by: Tim <hello@timsmart.co>

.changeset/dry-badgers-boil.md

@@ -0,0 +1,5 @@
+---
+"effect": minor
+---
+
+improve: type Fiber.awaitAll as Exit<A, E>[].

packages/effect/dtslint/Fiber.ts

@@ -0,0 +1,16 @@
+import { Fiber } from "effect"
+
+declare const string: Fiber.Fiber<string>
+declare const number: Fiber.Fiber<number>
+declare const array: Array<Fiber.Fiber<string> | Fiber.Fiber<number>>
+
+// awaitAll
+
+// $ExpectType Effect<[Exit<string, never>, Exit<number, never>], never, never>
+Fiber.awaitAll([string, number])
+
+// $ExpectType Effect<(Exit<string, never> | Exit<number, never>)[], never, never>
+Fiber.awaitAll(new Set([string, number]))
+
+// $ExpectType Effect<(Exit<string, never> | Exit<number, never>)[], never, never>
+Fiber.awaitAll(array)

packages/effect/src/Fiber.ts

@@ -275,7 +275,14 @@ export {
  * @since 2.0.0
  * @category destructors
  */
-export const awaitAll: (fibers: Iterable<Fiber<any, any>>) => Effect.Effect<void> = fiberRuntime.fiberAwaitAll
+export const awaitAll: <const T extends Iterable<Fiber<any, any>>>(
+  fibers: T
+) => Effect.Effect<
+  [T] extends [ReadonlyArray<infer U>]
+    ? number extends T["length"] ? Array<U extends Fiber<infer A, infer E> ? Exit.Exit<A, E> : never>
+    : { -readonly [K in keyof T]: T[K] extends Fiber<infer A, infer E> ? Exit.Exit<A, E> : never }
+    : Array<T extends Iterable<infer U> ? U extends Fiber<infer A, infer E> ? Exit.Exit<A, E> : never : never>
+> = fiberRuntime.fiberAwaitAll
 
 /**
  * Retrieves the immediate children of the fiber.

packages/effect/src/internal/fiberRuntime.ts

@@ -3288,8 +3288,14 @@ export const currentSupervisor: FiberRef.FiberRef<Supervisor.Supervisor<any>> =
 // circular with Fiber
 
 /* @internal */
-export const fiberAwaitAll = (fibers: Iterable<Fiber.Fiber<any, any>>): Effect.Effect<void> =>
-  core.asVoid(internalFiber._await(fiberAll(fibers)))
+export const fiberAwaitAll = <const T extends Iterable<Fiber.Fiber<any, any>>>(
+  fibers: T
+): Effect.Effect<
+  [T] extends [ReadonlyArray<infer U>]
+    ? number extends T["length"] ? Array<U extends Fiber.Fiber<infer A, infer E> ? Exit.Exit<A, E> : never>
+    : { -readonly [K in keyof T]: T[K] extends Fiber.Fiber<infer A, infer E> ? Exit.Exit<A, E> : never }
+    : Array<T extends Iterable<infer U> ? U extends Fiber.Fiber<infer A, infer E> ? Exit.Exit<A, E> : never : never>
+> => forEach(fibers, internalFiber._await) as any
 
 /** @internal */
 export const fiberAll = <A, E>(fibers: Iterable<Fiber.Fiber<A, E>>): Fiber.Fiber<Array<A>, E> => ({

packages/effect/test/Fiber.test.ts

@@ -210,7 +210,9 @@ describe("Fiber", () => {
   it.effect("awaitAll - stack safety", () =>
     Effect.gen(function*($) {
       const result = yield* $(Fiber.awaitAll(fibers))
-      assert.isUndefined(result)
+      assert.isArray(result)
+      assert(result.length === fibers.length)
+      result.forEach((_) => assert.isTrue(Exit.isSuccess(_) && _.value === undefined))
     }), 10000)
   it.effect("joinAll - stack safety", () =>
     Effect.gen(function*($) {