deepFreeze.ts

deepFreeze.ts

export type DeepReadonly<T> =
  T extends (string | number | symbol | boolean) ? T :
  T extends RegExp ? T :
  T extends Function ? T :
  T extends Map<infer K, infer V> ? ReadonlyMap<K, V> :
  T extends Set<infer E> ? ReadonlySet<E> :
  T extends (infer E)[] ? ReadonlyArray<Readonly<E>> : // FIXME: can we apply DeepReadonly to collection elements?
  T extends {} ? { readonly [k in keyof T]: DeepReadonly<T[k]>; }
  : never;

export function deepFreeze<T>(t: T): DeepReadonly<T> {
  return t as any;
}