export type Maybe<T> = T | null | undefined
export type Writable<T> = {
  -readonly [P in keyof T]: T[P] extends object ? Writable<T[P]> : T[P]
}
export type RemoveUndefined<T> = {
  [K in keyof T]-?: Exclude<T[K], undefined>
}

export type Left<E> = {
  tag: 'left'
  error: E
}

export type Right<T> = {
  tag: 'right'
  value: T
}

export type Either<E, T> = Left<E> | Right<T>

export type MaybePromise<T, IsAsync extends boolean> = IsAsync extends true
  ? Promise<T>
  : T