gistfile1.txt

fn compact<T>(x: &mut ~[T],
              keep: |&T| -> bool) {
    if x.len() == 0 {
        return;
    }

    let mut kept = 0;
    let mut finger = 0;
    let mut last = x.len() - 1;
    while finger <= last {
        if keep(&x[finger]) {
            x.swap(kept, finger);
            kept += 1;
        }
        finger += 1;
    }
    x.truncate(kept);
}

fn main() {
    let mut x: ~[uint] = ~[1, 2, 3, 4, 5, 6];
    compact(&mut x, |x| x % 2 == 0);
    println!("{:?}", x);
}