static <A, B> A mapLike foldl(F2<A, B, A> f, A seed, Iterable<B> l) {
  A a = seed;
  if (l != null) for(B b : l)
    a = callF(f, a, b);
  ret a;
}

static <A, B> A mapLike foldl(F2<A, B, A> f, A seed, B[] l) {
  A a = seed;
  if (l != null) for(B b : l)
    a = callF(f, a, b);
  ret a;
}

static <A, B> A mapLike foldl(O f, A seed, B[] l) {
  A a = seed;
  if (l != null) for(B b : l)
    a = (A) callF(f, a, b);
  ret a;
}