| // Copyright 2014 The Rust Project Developers. See the COPYRIGHT |
| // file at the top-level directory of this distribution and at |
| // http://rust-lang.org/COPYRIGHT. |
| // |
| // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or |
| // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license |
| // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your |
| // option. This file may not be copied, modified, or distributed |
| // except according to those terms. |
| |
| |
| #![allow(unknown_features)] |
| #![feature(box_patterns)] |
| #![feature(box_syntax)] |
| |
| #[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 Noun::Atom(2), box Noun::Cell(box Noun::Atom(2), box Noun::Atom(3)))); |
| } |
