// apply a function to an iterator
static IterableIterator mapI(final O f, final Iterator i) {
  ret new IterableIterator {
    public bool hasNext() {
      ret i.hasNext();
    }
    
    public O next() {
      ret callF(f, i.next());
    }
  };
}

ifclass IterableIterator
static IterableIterator mapI(IterableIterator i, O f) {
  ret mapI((Iterator) i, f);
}

static IterableIterator mapI(O f, IterableIterator i) {
  ret mapI((Iterator) i, f);
}
endif

static IterableIterator mapI(Iterator i, O f) {
  ret mapI(f, i);
}

static IterableIterator mapI(Iterable i, O f) {
  ret mapI(f, i.iterator());
}

static IterableIterator mapI(O f, Iterable i) {
  ret mapI(i, f);
}