Flip Arguments

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题目

Implement the type version of lodash's _.flip.

Type FlipArguments<T> requires function type T and returns a new function type which has the same return type of T but reversed parameters.

For example:

type Flipped = FlipArguments<(arg0: string, arg1: number, arg2: boolean) => void>
// (arg0: boolean, arg1: number, arg2: string) => void

解答

同 Reverse，

将函数的 args 套用 Reverse 进行反转即可：

type Reverse<T extends unknown[]> = T extends [infer F, ...infer R]
  ? [...Reverse<R>, F]
  : [];

type FlipArguments<T extends (...args: any[]) => any> = T extends (
  ...args: infer P
) => infer U
  ? (...args: Reverse<P>) => U
  : never;