export function merge<A>(m1: MMap<A>, m2: MMap<A>): MMap<A> {
  return I.unionWithKey((_, a, b) => L.append(a, b), m1, m2);
}

export function searchWith<A>(k: number, f: (_: A) => boolean, m: MMap<A>): Maybe<A> {
  const ret = I.lookup(k, m);
  return isNothing(ret) ? ret : L.find(f, ret.value);
}

export function search<A>(k: number, m: MMap<A>): Maybe<A> {
  return chainMaybe(I.lookup(k, m), L.head);
}

export function lookup<A>(h: number, k: string, hm: HashMap<A>): Maybe<A> {
  const ret = I.lookup(h, hm);
  return isNothing(ret) ? ret : M.lookup(k, ret.value);
}

export function insert<A>(h: number, k: string, v: A, m: HashMap<A>): HashMap<A> {
  return I.insertWith(M.union as any, h, M.singleton(k, v), m);
}