simplify EffectGenerator type (#2611)

Effect-TS · Apr 25, 2024 · 6222404 · 6222404
1 parent ba67a5b
commit 6222404
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Showing 7 changed files with 14 additions and 12 deletions.
diff --git a/.changeset/bright-snakes-occur.md b/.changeset/bright-snakes-occur.md
@@ -0,0 +1,5 @@
+---
+"effect": patch
+---
+
+simplify EffectGenerator type to improve inference
diff --git a/packages/effect/src/Effect.ts b/packages/effect/src/Effect.ts
@@ -101,11 +101,8 @@ export interface Effect<out A, out E = never, out R = never> extends Effect.Vari
  * @since 3.0.0
  * @category models
  */
-export interface EffectGenerator<Eff extends Effect<any, any, any>> {
-  next(...args: ReadonlyArray<any>): IteratorResult<Eff, Effect.Success<Eff>>
-  return(value: Effect.Success<Eff>): IteratorResult<Eff, Effect.Success<Eff>>
-  throw(e: any): IteratorResult<Eff, Effect.Success<Eff>>
-  [Symbol.iterator](): EffectGenerator<Eff>
+export interface EffectGenerator<T extends Effect<any, any, any>> {
+  next(...args: ReadonlyArray<any>): IteratorResult<T, Effect.Success<T>>
 }
 
 /**
@@ -1123,15 +1120,15 @@ export const dieSync: (evaluate: LazyArg<unknown>) => Effect<never> = core.dieSy
  */
 export const gen: {
   <Eff extends Effect<any, any, any>, AEff>(
-    f: (resume: Adapter) => Generator<Eff, AEff, any>
+    f: (resume: Adapter) => Generator<Eff, AEff, never>
   ): Effect<
     AEff,
     [Eff] extends [never] ? never : [Eff] extends [Effect<infer _A, infer E, infer _R>] ? E : never,
     [Eff] extends [never] ? never : [Eff] extends [Effect<infer _A, infer _E, infer R>] ? R : never
   >
   <Self, Eff extends Effect<any, any, any>, AEff>(
     self: Self,
-    f: (this: Self, resume: Adapter) => Generator<Eff, AEff, any>
+    f: (this: Self, resume: Adapter) => Generator<Eff, AEff, never>
   ): Effect<
     AEff,
     [Eff] extends [never] ? never : [Eff] extends [Effect<infer _A, infer E, infer _R>] ? E : never,

diff --git a/packages/effect/src/Either.ts b/packages/effect/src/Either.ts
@@ -713,7 +713,7 @@ export const gen: Gen.Gen<EitherTypeLambda, Gen.Adapter<EitherTypeLambda>> = (f)
       return current
     }
     while (!state.done) {
-      state = iterator.next(current.right)
+      state = iterator.next(current.right as never)
       if (!state.done) {
         current = state.value
         if (isLeft(current)) {

diff --git a/packages/effect/src/Option.ts b/packages/effect/src/Option.ts
@@ -1276,7 +1276,7 @@ export const gen: Gen.Gen<OptionTypeLambda, Gen.Adapter<OptionTypeLambda>> = (f)
       return current
     }
     while (!state.done) {
-      state = iterator.next(current.value)
+      state = iterator.next(current.value as never)
       if (!state.done) {
         current = state.value
         if (isNone(current)) {

diff --git a/packages/effect/src/STM.ts b/packages/effect/src/STM.ts
@@ -1065,7 +1065,7 @@ export interface Adapter {
  * @category constructors
  */
 export const gen: <Eff extends STM<any, any, any>, AEff>(
-  f: (resume: Adapter) => Generator<Eff, AEff, any>
+  f: (resume: Adapter) => Generator<Eff, AEff, never>
 ) => STM<
   AEff,
   [Eff] extends [never] ? never : [Eff] extends [STM<infer _A, infer E, infer _R>] ? E : never,

diff --git a/packages/effect/src/Utils.ts b/packages/effect/src/Utils.ts
@@ -174,7 +174,7 @@ export interface Variance<in out F extends TypeLambda, in R, out O, out E> {
  */
 export interface Gen<F extends TypeLambda, Z> {
   <K extends Variance<F, any, any, any> | Kind<F, any, any, any, any>, A>(
-    body: (resume: Z) => Generator<K, A>
+    body: (resume: Z) => Generator<K, A, never>
   ): Kind<
     F,
     [K] extends [Variance<F, infer R, any, any>] ? R : [K] extends [Kind<F, infer R, any, any, any>] ? R : never,

diff --git a/packages/effect/src/internal/stm/stm.ts b/packages/effect/src/internal/stm/stm.ts
@@ -626,7 +626,7 @@ export const gen: typeof STM.gen = (f) =>
     ): STM.STM<any, any, any> =>
       state.done ?
         core.succeed(state.value) :
-        core.flatMap(state.value, (val: any) => run(iterator.next(val)))
+        core.flatMap(state.value, (val: any) => run(iterator.next(val as never)))
     return run(state)
   })