brainfuck.rs

import io::*;
import to_str::*;

enum some_enum {
    foo(~[some_enum]),
    bar
}

impl to_str for some_enum {
    fn to_str() -> str {
        alt self {
            bar       { "bar" }
            foo(nest) { "foo[" + nest.to_str() + "]" } // can't do this
            /* but can do this:
            foo(nest) {
                let mut result = "foo[";
                for nest.each() |n| {
                    result += n.to_str();
                }
                result += "]";
                result
            }
            */
        }
    }
}

fn main() {
    let quxx = foo(~[foo(~[bar])]);
    println(quxx.to_str());
}

~~~~~~~~~~~~~~~~~~~ compilation result ~~~~~~~~~~~~~~~~~~~~~~
user@note ~/soft/mine/rust $ rustc brainfuck.rs && echo done &&  ./brainfuck
brainfuck.rs:13:33: 13:44 error: failed to find an implementation of interface core::to_str::to_str for some_enum
brainfuck.rs:13             foo(nest) { "foo[" + nest.to_str() + "]" } // can't do this