gistfile1.rs

use std::io;

#[deriving(Show)]
enum List {
    Cons(~str, ~List),
    Nil
}

fn print_list( lst : &List ) {
    match lst {
        &Cons( ref x, ref xs ) => {
            println!( "Node: '{}'", x );
            print_list( *xs );
        }
        &Nil => { println!( "Nil" ) }
    }
}

fn main() {
    let mut head : List = Nil;

    for line in io::stdin().lines() {
        let input = line.unwrap();
        println!("You typed: '{}'", input.trim());
        let words : ~[&str] = input.words().collect();
        match words.as_slice() {
            ["show"]    => {
                print_list(&head);
                println!("{}", &head);
            }
            ["push", x] => {
                println!("Pushing '{}'", x);
                head = Cons( x.to_owned(), box head);
            }
            ["pop"]     => {
                println!("Popping")
                match head {
                    Cons( x, ~xs ) => {
                        head = xs;
                        println!("Popped an '{}'", x);
                    }
                    Nil => {
                        println!("Can't pop an empty list");
                    }
                }
            }
            ["exit"]     => {
                println!("Bye!");
                break;
            }
            _      => println!("I don't understand")
        }
    }
}