Preserve Array.modify and Array.modifyOption non emptiness (Effec…

…t-TS#3496)

.changeset/curvy-cats-smoke.md

@@ -0,0 +1,5 @@
+---
+"effect": minor
+---
+
+preserve `Array.modify` `Array.modifyOption` non emptiness

packages/effect/dtslint/Array.ts

@@ -1363,6 +1363,9 @@ pipe(nonEmptyNumbers, Array.replace(0, "a" as const))
 // $ExpectType ("a" | 1 | 2)[]
 pipe(new Set([1, 2] as const), Array.replace(0, "a" as const))
 
+// $ExpectType [number | "a", ...(number | "a")[]]
+pipe(Array.of(1), Array.replace(0, "a" as const))
+
 // -------------------------------------------------------------------------------------
 // replaceOption
 // -------------------------------------------------------------------------------------
@@ -1390,3 +1393,114 @@ pipe(nonEmptyNumbers, Array.replaceOption(0, "a" as const))
 
 // $ExpectType Option<("a" | 1 | 2)[]>
 pipe(new Set([1, 2] as const), Array.replaceOption(0, "a" as const))
+
+// -------------------------------------------------------------------------------------
+// modify
+// -------------------------------------------------------------------------------------
+
+// $ExpectType string[]
+Array.modify([], 0, (
+  _n // $ExpectType never
+) => "a")
+// $ExpectType (string | number)[]
+Array.modify(numbers, 0, (
+  _n // $ExpectType number
+) => "a")
+
+// $ExpectType [number | "a", ...(number | "a")[]]
+Array.modify(nonEmptyNumbers, 0, (
+  _n // $ExpectType number
+) => "a" as const)
+
+// $ExpectType ("a" | 1 | 2)[]
+Array.modify(new Set([1, 2] as const), 0, (
+  _n // $ExpectType 1 | 2
+) => "a" as const)
+
+// $ExpectType string[]
+pipe(
+  [],
+  Array.modify(0, (
+    _n // $ExpectType never
+  ) => "a")
+)
+
+// $ExpectType (string | number)[]
+pipe(
+  numbers,
+  Array.modify(0, (
+    _n // $ExpectType number
+  ) => "a")
+)
+
+// $ExpectType [number | "a", ...(number | "a")[]]
+pipe(
+  nonEmptyNumbers,
+  Array.modify(0, (
+    _n // $ExpectType number
+  ) => "a" as const)
+)
+
+// $ExpectType ("a" | 1 | 2)[]
+pipe(
+  new Set([1, 2] as const),
+  Array.modify(0, (
+    _n // $ExpectType 1 | 2
+  ) => "a" as const)
+)
+
+// -------------------------------------------------------------------------------------
+// modifyOption
+// -------------------------------------------------------------------------------------
+
+// $ExpectType Option<string[]>
+Array.modifyOption([], 0, (
+  _n // $ExpectType never
+) => "a")
+
+// $ExpectType Option<(string | number)[]>
+Array.modifyOption(numbers, 0, (
+  _n // $ExpectType number
+) => "a")
+
+// $ExpectType Option<[number | "a", ...(number | "a")[]]>
+Array.modifyOption(nonEmptyNumbers, 0, (
+  _n // $ExpectType number
+) => "a" as const)
+
+// $ExpectType Option<("a" | 1 | 2)[]>
+Array.modifyOption(new Set([1, 2] as const), 0, (
+  _n // $ExpectType 1 | 2
+) => "a" as const)
+
+// $ExpectType Option<string[]>
+pipe(
+  [],
+  Array.modifyOption(0, (
+    _n // $ExpectType never
+  ) => "a")
+)
+
+// $ExpectType Option<(string | number)[]>
+pipe(
+  numbers,
+  Array.modifyOption(0, (
+    _n // $ExpectType number
+  ) => "a")
+)
+
+// $ExpectType Option<[number | "a", ...(number | "a")[]]>
+pipe(
+  nonEmptyNumbers,
+  Array.modifyOption(0, (
+    _n // $ExpectType number
+  ) => "a" as const)
+)
+
+// $ExpectType Option<("a" | 1 | 2)[]>
+pipe(
+  new Set([1, 2] as const),
+  Array.modifyOption(0, (
+    _n // $ExpectType 1 | 2
+  ) => "a" as const)
+)

packages/effect/src/Array.ts

@@ -1109,8 +1109,15 @@ export const replaceOption: {
  * @since 2.0.0
  */
 export const modify: {
-  <A, B>(i: number, f: (a: A) => B): (self: Iterable<A>) => Array<A | B>
-  <A, B>(self: Iterable<A>, i: number, f: (a: A) => B): Array<A | B>
+  <A, B, S extends Iterable<A> = Iterable<A>>(
+    i: number,
+    f: (a: ReadonlyArray.Infer<S>) => B
+  ): (self: S) => ReadonlyArray.With<S, ReadonlyArray.Infer<S> | B>
+  <A, B, S extends Iterable<A> = Iterable<A>>(
+    self: S,
+    i: number,
+    f: (a: ReadonlyArray.Infer<S>) => B
+  ): ReadonlyArray.With<S, ReadonlyArray.Infer<S> | B>
 } = dual(
   3,
   <A, B>(self: Iterable<A>, i: number, f: (a: A) => B): Array<A | B> =>
@@ -1134,8 +1141,15 @@ export const modify: {
  * @since 2.0.0
  */
 export const modifyOption: {
-  <A, B>(i: number, f: (a: A) => B): (self: Iterable<A>) => Option<Array<A | B>>
-  <A, B>(self: Iterable<A>, i: number, f: (a: A) => B): Option<Array<A | B>>
+  <A, B, S extends Iterable<A> = Iterable<A>>(
+    i: number,
+    f: (a: ReadonlyArray.Infer<S>) => B
+  ): (self: S) => Option<ReadonlyArray.With<S, ReadonlyArray.Infer<S> | B>>
+  <A, B, S extends Iterable<A> = Iterable<A>>(
+    self: S,
+    i: number,
+    f: (a: ReadonlyArray.Infer<S>) => B
+  ): Option<ReadonlyArray.With<S, ReadonlyArray.Infer<S> | B>>
 } = dual(3, <A, B>(self: Iterable<A>, i: number, f: (a: A) => B): Option<Array<A | B>> => {
   const out = Array.from(self)
   if (isOutOfBound(i, out)) {