how do i link list

list.rs

use std::fmt::Default;

enum List<T> {
  Cons(T, ~List<T>),
  Nil
}

fn cons<T>(x: T, xs: List<T>) -> List<T> {
  Cons(x, ~xs)
}

fn tail<'a, T>(xs: &'a List<T>) -> &'a List<T> {
  match xs {
    &Cons(_, ~ref ys) => ys,
    &Nil => fail!("Cannot take the tail of an empty list")
  }
}

fn print_list<T: Default>(xs: &List<T>) {
  match (xs) {
    &Nil => println!("End of list"),
    &Cons(ref x, ~ref ys) => {
      println!("Found cons cell: {}", *x);
      print_list(ys)
    }
  }
}

fn main() {
  let list = cons(1, cons(2, cons(3, Nil)));
  print_list(&list);

  let list_two = tail(&list);
  print_list(list_two);

  print_list(&list);

}