feat(types): TupleToUnion

Signed-off-by: Lexus Drumgold <[email protected]>

src/types/__tests__/tuple-to-union.spec-d.ts

@@ -0,0 +1,16 @@
+/**
+ * @file Type Tests - TupleToUnion
+ * @module tutils/types/tests/unit-d/TupleToUnion
+ */
+
+import type TestSubject from '../tuple-to-union'
+
+describe('unit-d:types/TupleToUnion', () => {
+  it('should equal tuple elements union if T is a tuple', () => {
+    expectTypeOf<TestSubject<[0, 1, 2]>>().toEqualTypeOf<0 | 1 | 2>()
+  })
+
+  it('should equal never if T is not a tuple', () => {
+    expectTypeOf<TestSubject<number>>().toBeNever()
+  })
+})

src/types/index.ts

@@ -93,4 +93,5 @@ export type { default as Promisable } from './promisable'
 export type { default as Simplify } from './simplify'
 export type { default as Split } from './split'
 export type { default as Stringafiable } from './stringafiable'
+export type { default as TupleToUnion } from './tuple-to-union'
 export type { default as TypedArray } from './typed-array'

src/types/tuple-to-union.ts

@@ -0,0 +1,16 @@
+/**
+ * @file Type Definitions - TupleToUnion
+ * @module tutils/types/TupleToUnion
+ */
+
+/**
+ * Converts a [tuple][1] to a [union][2].
+ *
+ * [1]: https://www.codecademy.com/resources/docs/typescript/tuples
+ * [2]: https://www.typescriptlang.org/docs/handbook/unions-and-intersections#union-types
+ *
+ * @template T - Type to evaluate
+ */
+type TupleToUnion<T> = T extends readonly unknown[] ? T[number] : never
+
+export type { TupleToUnion as default }