rust fizz buzz

buzz.rs

use std::collections::HashMap;

type BuzzFn<'a> = Box<(Fn(i32) -> String) + 'a>;

fn mbfn<'a, F>(f: F) -> BuzzFn<'a>
    where F: Fn(i32) -> String + 'a {
        Box::new(f) as BuzzFn
}

fn do_buzz() {
    fn test(x:i32) -> (bool,bool) {
        (x % 3 == 0, x % 5 == 0)
    }

    let mut table = HashMap::new();

    table.insert((false,false),  mbfn(|x:i32| { x.to_string() }));
    table.insert((true ,false),  mbfn(|x:i32| { "Fizz".to_string() }));
    table.insert((false,true),   mbfn(|x:i32| { "Buzz".to_string() }));
    table.insert((true ,true),   mbfn(|x:i32| { "FizzBuzz".to_string() }));

    for x in 1..31 {
        println!("{:}", table.get(&test(x)).map(|f| f(x)).unwrap());
    }


}

fn main() {
    do_buzz();
}