gistfile1.rs

use std::util;
enum List {
    Cons(int, ~List),
    Nil
}

impl List {
    fn prepend(&mut self, x : int) {
        let new = ~util::replace(self, Nil);
        *self = Cons(x, new);
    }
}

fn main() {
    let mut li = Cons(2, ~Nil);
    li.prepend(1);
    println!("{:?}", li);
}