gistfile1.rs

enum List_ {
    Cons(int, ~List_),
    Nil
}

struct List(~List_);

impl List {
    fn prepend(&mut self, x : int) {
        let List(old) = self; // I have no idea, how to write this line
        *self = List(~Cons(x, old));
    }
}

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