Rust vector shortening

gistfile1.rs

import vec::*;

fn truncate<T>(&v: ~[const T], newlen: uint) {
    let oldlen = len(v);
    assert(newlen <= oldlen);
    unsafe {
        for uint::range(newlen, oldlen) |i| {
            let _dropped <- *ptr::mut_addr_of(v[i]);
        }
        unsafe::set_len(v, newlen);
    }
}

#[cfg(test)]
use std;

#[test]
fn test_truncate() {
    let mut v = ~[@6,@5,@4];
    truncate(v, 1);
    assert(v.len() == 1);
    assert(*(v[0]) == 6);
}