Functional style quicksort in Rustlang

quicksort.rs

fn quicksort<E: PartialOrd + Clone>(list: &[E]) -> Vec<E> {
    let pivot = match list.get(0) {
        None => return vec![],
        Some(v) => v,
    };
    let less: Vec<_> = list[1..].iter().filter(|&e| e <= pivot).cloned().collect();
    let more: Vec<_> = list.iter().filter(|&e| e > pivot).cloned().collect();
    [quicksort(&less), vec![pivot.clone()], quicksort(&more)].concat()
}

fn main() {
    assert_eq!(vec![1, 2, 4, 5, 5, 6, 6, 7, 9, 13], quicksort(&[5, 5, 2, 1, 6, 13, 7, 9, 4, 6]));
}