Ensure Chunk.reverse preserves NonEmpty status, closes #2947 (#2950)

.changeset/cold-kangaroos-chew.md

@@ -0,0 +1,5 @@
+---
+"effect": patch
+---
+
+Ensure `Chunk.reverse` preserves `NonEmpty` status, closes #2947

packages/effect/dtslint/Chunk.ts

@@ -471,3 +471,19 @@ flattenNonEmptyChunk.pipe(Effect.map((_) => Chunk.flatten(_)))
 
 // $ExpectType Effect<NonEmptyChunk<number>, never, never>
 flattenNonEmptyChunk.pipe(Effect.map(Chunk.flatten))
+
+// -------------------------------------------------------------------------------------
+// reverse
+// -------------------------------------------------------------------------------------
+
+// $ExpectType Chunk<number>
+Chunk.reverse(numbers)
+
+// $ExpectType Chunk<number>
+pipe(numbers, Chunk.reverse)
+
+// $ExpectType NonEmptyChunk<number>
+Chunk.reverse(nonEmptyNumbers)
+
+// $ExpectType NonEmptyChunk<number>
+pipe(nonEmptyNumbers, Chunk.reverse)

packages/effect/src/Chunk.ts

@@ -316,11 +316,7 @@ export const toReadonlyArray = <A>(self: Chunk<A>): ReadonlyArray<A> => {
   }
 }
 
-/**
- * @since 2.0.0
- * @category elements
- */
-export const reverse = <A>(self: Chunk<A>): Chunk<A> => {
+const reverseChunk = <A>(self: Chunk<A>): Chunk<A> => {
   switch (self.backing._tag) {
     case "IEmpty":
     case "ISingleton":
@@ -336,6 +332,22 @@ export const reverse = <A>(self: Chunk<A>): Chunk<A> => {
   }
 }
 
+/**
+ * Reverses the order of elements in a `Chunk`.
+ * Importantly, if the input chunk is a `NonEmptyChunk`, the reversed chunk will also be a `NonEmptyChunk`.
+ *
+ * @example
+ * import { Chunk } from "effect"
+ *
+ * const numbers = Chunk.make(1, 2, 3)
+ * const reversedNumbers = Chunk.reverse(numbers)
+ * assert.deepStrictEqual(reversedNumbers, Chunk.make(3, 2, 1))
+ *
+ * @since 2.0.0
+ * @category elements
+ */
+export const reverse: <S extends Chunk<any>>(self: S) => Chunk.With<S, Chunk.Infer<S>> = reverseChunk as any
+
 /**
  * This function provides a safe way to read a value at a particular index from a `Chunk`.
  *