CheckRepeatedTuple

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题目

判断一个元组类型中是否有相同的成员

For example:

type CheckRepeatedTuple<[1, 2, 3]>   // false
type CheckRepeatedTuple<[1, 2, 1]>   // true

解答

type CheckRepeatedTuple<T extends unknown[]> = T extends [infer L, ...infer R]
  ? L extends R[number]
    ? true
    : CheckRepeatedTuple<R>
  : false;