| //@ run-pass | |
| #![feature(box_patterns)] | |
| #[derive(Clone)] | |
| enum Noun | |
| { | |
| Atom(isize), | |
| Cell(Box<Noun>, Box<Noun>) | |
| } | |
| fn fas(n: &Noun) -> Noun | |
| { | |
| match n { | |
| &Noun::Cell(box Noun::Atom(2), box Noun::Cell(ref a, _)) => (**a).clone(), | |
| _ => panic!("Invalid fas pattern") | |
| } | |
| } | |
| pub fn main() { | |
| fas( | |
| &Noun::Cell(Box::new(Noun::Atom(2)), | |
| Box::new(Noun::Cell(Box::new(Noun::Atom(2)), Box::new(Noun::Atom(3))))) | |
| ); | |
| } |