fn merge_sort<T: Ord + Copy>(data: &mut [T]) {
    fn merge<T: Ord + Copy>(left: &mut [T], right: &mut [T], util: &mut [T]) {
        let left = left.iter();
        let right = right.iter();

        left.zip(right).fold(0usize, |index, (l, r)| {
            if l < r {
                util[index] = *l;
                util[index + 1] = *r;
            }
            else {
                util[index] = *r;
                util[index + 1] = *l;
            }

            index + 2
        });
    }

    fn copy<T: Ord + Copy>(data: &mut [T], util: &mut [T]) {

    }

    fn tick<T: Ord + Copy>(data: &mut [T], util: &mut [T]) {
        if data.len() < 2 {
            return
        }

        let middle = data.len() / 2;

        let (data_left, data_right) = data.split_at_mut(middle);
        let (util_left, util_right) = util.split_at_mut(middle);

        tick(data_left, util_left);
        tick(data_right, util_right);

        merge(data_left, data_right, util);

        copy(data, util);
    }

    let len = data.len();

    if len < 2 {
        return
    }

    let ref mut util: Vec<T> = Vec::with_capacity(len);

    tick(data, util.as_mut_slice());
}

fn main() {
    let ref mut data: [u32; 7] = [38, 27, 43, 3, 9, 82, 10];

    merge_sort(data);

    println!("{:?}", data);
}