Get the permutations of a union type

permutations.ts

export type Permutations<T, TInitial = T> = T extends infer TSingle
  ?
      | [TSingle]
      | (Permutations<Exclude<TInitial, TSingle>> extends infer TPermutation
          ? TPermutation extends any[]
            ? [T | TPermutation[number]]
            : never
          : never)
  : never

export type RecordPermutations<
  K extends PropertyKey,
  V,
> = Permutations<K> extends infer TPermutation
  ? TPermutation extends [infer K extends PropertyKey]
    ? Record<K, V>
    : never
  : never