898-includes.ts

/*
  898 - Includes
  -------
  by null (@kynefuk) #简单 #array

  ### 题目

  在类型系统里实现 JavaScript 的 `Array.includes` 方法，这个类型接受两个参数，返回的类型要么是 `true` 要么是 `false`。

  例如：

  ```ts
  type isPillarMen = Includes<['Kars', 'Esidisi', 'Wamuu', 'Santana'], 'Dio'> // expected to be `false`
  ```

  > 在 Github 上查看：https://tsch.js.org/898/zh-CN
*/

/* _____________ 你的代码 _____________ */

type IsEqual<X, Y> =
    (<T>() => T extends X ? 1 : 2) extends
    (<T>() => T extends Y ? 1 : 2) ? true : false;

type Includes<T extends readonly unknown[], U> =
    T extends [infer First, ...infer Rest]
        ? IsEqual<First, U> extends true
            ? true
            : Includes<Rest, U>
        : false;


/* _____________ 测试用例 _____________ */
import type { Equal, Expect } from '@type-challenges/utils'

type cases = [
    Expect<Equal<Includes<['Kars', 'Esidisi', 'Wamuu', 'Santana'], 'Kars'>, true>>,
    Expect<Equal<Includes<['Kars', 'Esidisi', 'Wamuu', 'Santana'], 'Dio'>, false>>,
    Expect<Equal<Includes<[1, 2, 3, 5, 6, 7], 7>, true>>,
    Expect<Equal<Includes<[1, 2, 3, 5, 6, 7], 4>, false>>,
    Expect<Equal<Includes<[1, 2, 3], 2>, true>>,
    Expect<Equal<Includes<[1, 2, 3], 1>, true>>,
    Expect<Equal<Includes<[{}], { a: 'A' }>, false>>,
    Expect<Equal<Includes<[boolean, 2, 3, 5, 6, 7], false>, false>>,
    Expect<Equal<Includes<[true, 2, 3, 5, 6, 7], boolean>, false>>,
    Expect<Equal<Includes<[false, 2, 3, 5, 6, 7], false>, true>>,
    Expect<Equal<Includes<[{ a: 'A' }], { readonly a: 'A' }>, false>>,
    Expect<Equal<Includes<[{ readonly a: 'A' }], { a: 'A' }>, false>>,
    Expect<Equal<Includes<[1], 1 | 2>, false>>,
    Expect<Equal<Includes<[1 | 2], 1>, false>>,
    Expect<Equal<Includes<[null], undefined>, false>>,
    Expect<Equal<Includes<[undefined], null>, false>>,
]

/* _____________ 下一步 _____________ */
/*
  > 分享你的解答：https://tsch.js.org/898/answer/zh-CN
  > 查看解答：https://tsch.js.org/898/solutions
  > 更多题目：https://tsch.js.org/zh-CN
*/