public static <A> int count(Iterable<A> l1,
			final F1<A, Boolean> f1) {
        final int[] count = new int[] {0};
        each(l1, new P1<A>() { public void e(A obj) {
            if (f1.e(obj)) {
                count[0] ++;
            }
        }});
		return count[0];
	}