rambdax/_ts-toolbelt/src/Union/Last.ts

Extended version of Rambda - a lightweight, faster alternative to Ramda

import {IntersectOf} from './IntersectOf'
import {Union} from './Union'

/**
Get the last item within an [[Union]]
(⚠️ it might not preserve order)
@param U
@returns [[Any]]
@example
```ts
```
*/
export type Last<U extends Union> =
    IntersectOf<
        U extends unknown   // Distribute U
        ? (x: U) => void
        : never             // To intersect
    > extends (x: infer P) => void
      ? P                   // Extract merged
      : never               // ^^^ Last parameter

// The above does this (i.e.)
// ParamsOf<((a: 1) => void) & ((a: 2) => void)> // => [2]