A minmal example of merge sort in Rust

merge_sort.rs

use rand::Rng;

fn merge_sort<T: Ord + Clone + Copy>(arr: &mut [T]) {
    let len = arr.len();
    if len < 2 {
        return;
    }
    let mid = len / 2;
    merge_sort(&mut arr[0..mid]);
    merge_sort(&mut arr[mid..]);

    let mut temp = arr.to_vec();
    let (left, right) = temp.split_at_mut(mid);     // mutable borrow
    let (mut i, mut j, mut k) = (0, 0, 0);
    while i < left.len() && j < right.len() {
        if left[i] <= right[j] {
            arr[k] = left[i].clone();
            i += 1;
        } else {
            arr[k] = right[j].clone();
            j += 1;
        }
        k += 1;
    }
    while i < left.len() {
        arr[k] = left[i].clone();
        i += 1;
        k += 1;
    }
    while j < right.len() {
        arr[k] = right[j].clone();
        j += 1;
        k += 1;
    }
}

fn main() {
    let mut rng = rand::thread_rng();
    let n: u32 = rng.gen_range(10..100);
    let mut arr = vec![0; n as usize];
    for i in 0..arr.len() {
        arr[i] = rng.gen_range(0..100);
    }

    println!("Before sorting: {:?}", arr);
    merge_sort(&mut arr);
    println!("After sorting: {:?}", arr)
}