map_cast Rust macro

map_cast.rs

use to_str::ToStr;

macro_rules! map_cast(
    (~[$($elems:expr),+] -> $T:ty) => (~[$($elems as $T),+]);
    (@[$($elems:expr),+] -> $T:ty) => (@[$($elems as $T),+]);
    ($arr:expr -> $T:ty) => ($arr.map(|a| *a as $T));
)

fn main() {
    let arr1 = map_cast!(~[1, 2.5] -> ToStr);
    io::println(fmt!("%?", arr1.map(|x| x.to_str())));
    
    let arr2 = map_cast!(@[1, 2.5] -> ToStr);
    io::println(fmt!("%?", arr2.map(|x| x.to_str())));
    
    let arr3 = ~[1.0, 2.5];
    io::println(fmt!("%?", map_cast!(arr3 -> ToStr).map(|x| x.to_str())));
    
    let char_arr = @['4', 'b', '&'];
    io::println(fmt!("%?", map_cast!(char_arr -> u8)));
    
    io::println(fmt!("%?", map_cast!(~[0.5, 1.0, 1.5] + ~[2.0, 2.5, 3.0] -> int)));
    
    // we run into the float casting problem here as well
    // io::println(fmt!("%?", map_cast!(~[0.5, 1, 1.5] + ~[2, 2.5, 3] -> int)));
    
    // the 'map' trait is not implemented for unique strings
    // io::println(fmt!("%?", map_cast!(~"xyz" + ~"23" -> u8)));
}