static <A> A[] repF_array(int n, IF0<A> f) {
  A[] a = cast new O[n];
  for i to n:
    a[i] = f.get();
  ret a;
}

static <A> A[] nuLike repF_array(Class<A> type, int n, IF0<A> f) {
  A[] a = newArrayOfType(type, n);
  for i to n:
    a[i] = f.get();
  ret a;
}