static <A> O[] mapToArrayOrNull(A[] l, IF1<A, O> f) {
  if (l == null) null;
  int n = l.length;
  if (n == 0) null;
  O[] array = new[n];
  for i to n:
    array[i] = f.get(l[i]);
  ret array;
}
  
static <A> O[] lambdaMapLike mapToArrayOrNull(IF1<A, O> f, A[] l) {
  ret mapToArrayOrNull(l, f);
}