Map example in Rust

powers.rs

extern mod std;

fn main() {
    let powers = [1, 2, 3, 4].map(|x| *x * *x);
    for powers.each |num| {
        io::println(int::str(*num));
    }
}

/*
Working version of this example:

    let powers = [1, 2, 3, 4].map(|x| x ** 2);

from http://lucumr.pocoo.org/2012/10/18/such-a-little-thing/

The problems with that code are:
 1. There's no ** operator in Rust. Like C, you have to call a function
    for exponentiation. For squaring, you can of course do "x * x"
 2. map() passes a reference to the array object, not the object itself.
    So type of x is &int, not int, and we must dereference it,
    returning "(*x) * (*x)" or "*x * *x"
*/

package main

func main() {
    powers := func(nums []int) (squares []int) {
        for _, x := range nums {
            squares = append(squares, x*x)
        }
        return
    }([]int{1,2,3,4})

    for _, num := range powers {
        println(num)
    }
}

Let me know when it's concurrency time.