gistfile1.txt

    iface i { fn foo() -> self<>; }
    fn foo<T:i>(v: T) -> T {
        ret v.foo();
    }
    impl of i for uint {
        fn foo() -> uint { ret self; }
    }
    fn main() {
        let x: i = 3u as i;
        let y = foo(x); // y has type i, but is in fact a uint
    }