utils.ts

export type Includes<T, Item> =
  T extends [infer First, ...infer Rest] ?
    First extends Item ?
      true
    : Includes<Rest, Item>
  : false

export type ConcatIfNotFound<T extends unknown[], Item> = Includes<
  T,
  Item
> extends true ?
  T
: [...T, Item]

export type Prettify<T> = {
  [K in keyof T]: T[K] extends object ? Prettify<T[K]> : T[K]
} & unknown

type pretty = Prettify<{ k1: 'v1' } & { k2: 'v2' }>

export type And<A, B> =
  A extends true ?
    B extends true ?
      true
    : false
  : false

type testAnd = And<true, false>
type testAnd1 = And<true, true>

export type Or<A, B> =
  A extends true ? true
  : B extends true ? true
  : false

type testOr = Or<true, false>
type testOr1 = Or<false, false>

// want empty to be last case
export type NotEmpty<S extends string> = S extends '' ? false : true

// T extends never won't work
export type IsNever<T> = [T] extends [never] ? true : false

// (1 | 2)[] extends (1[] | 2[])
export type IsUnion<T> = T[] extends (T extends T ? T[] : never) ? false : true

export type DeepMutable<T> = {
  -readonly [K in keyof T]: T[K] extends (
    Record<string, unknown> | readonly unknown[]
  ) ?
    DeepMutable<T[K]>
  : T[K]
}