pure unique lists

gistfile1.rs

enum list<T> {
    cons(T, ~list<T>),
    nil,
}

fn iter<T>(xs: list<T>, f: fn(T)) {
    alt xs {
      cons(x, xs) {
        f(x);
        iter::<T>(*xs, f)
      }
      nil { }
    }
}

fn main() {
    let xs = cons(~"a", ~cons(~"b", ~cons(~"c", ~nil)));

    iter(xs, |x| #error("%?", x));
    iter(xs, |x| #error("%?", x));
}