static <A, B> L<B> lambdaMapLike lazilyMap(IF1<A, B> f, L<A> l) {
  ret lazyMap((O) f, l);
}

static L lazilyMap(fO f, fL l) {
  ret new RandomAccessAbstractList {
    final int size = l(l);
    new HashMap<Int, O> data;
    
    public int size() { ret size; }
    public O get(int i) {
      if (data.containsKey(i))
        ret data.get(i);
      O o = callF(f, l.get(i));
      data.put(i, o);
      ret o;
    }
  };
}

static <A, B> L<B> lazilyMap(L<A> l, IF1<A, B> f) {
  ret lazilyMap(f, l);
}