// ============= Test Cases =============
import type { Equal, Expect } from './test-utils'

type A1 = TupleToUnion<[123, '456', true]>
type B1 = 123 | '456' | true;
type C1 = Expect<Equal<A1, B1>>;

type A2 = TupleToUnion<[123]>
type B2 = 123;
type C2 = Expect<Equal<A2, B2>>;

// ============= Your Code Here =============
type TupleToUnion<T extends unknown[]> = T[number];

// ============== Alternatives ==============
type TupleToUnion<T> =
  T extends unknown[]
  ? T[number]
  : never;

type TupleToUnion<T> = T[number & keyof T];

// using builtin `Extract`
type Extract<T, U> = T extends U ? T : never;
type TupleToUnion<T> = T[Extract<keyof T, number>];

type TupleToUnion<T> =
  T extends (infer R)[]
  ? R
  : never;

type TupleToUnion<T> =
  T extends [infer Head, ...infer Tail]
  ? Head | TupleToUnion<Tail>
  : never;

type TupleToUnion<T> = T[any];

type TupleToUnion<T extends any[]> = keyof {
  [K in T[number]]: K;
};