TypeScript type to return a deep readonly object (recursively)

index.ts

export type Primitive = string | number | boolean | bigint | symbol | undefined | null;
export type Builtin = Primitive | Function | Date | Error | RegExp;

/**
 * TypeScript type to return a deep readonly object (recursively).
 */
// prettier-ignore
export type DeepReadonly<T> = T extends Builtin
    ? T
    : T extends Map<infer K, infer V>
        ? ReadonlyMap<DeepReadonly<K>, DeepReadonly<V>>
        : T extends ReadonlyMap<infer K, infer V>
            ? ReadonlyMap<DeepReadonly<K>, DeepReadonly<V>>
            : T extends WeakMap<infer K, infer V>
                ? WeakMap<DeepReadonly<K>, DeepReadonly<V>>
                : T extends Set<infer U>
                    ? ReadonlySet<DeepReadonly<U>>
                    : T extends ReadonlySet<infer U>
                        ? ReadonlySet<DeepReadonly<U>>
                        : T extends WeakSet<infer U>
                            ? WeakSet<DeepReadonly<U>>
                            : T extends Promise<infer U>
                                ? Promise<DeepReadonly<U>>
                                : T extends (infer U)[]
                                    ? DeepReadonly<U>[]
                                    : T extends {}
                                        ? { readonly [K in keyof T]: DeepReadonly<T[K]> }
                                        : Readonly<T>