formats

this crate adds the formats!(), prints!(), and printlns!() macros, which work just like the standard format!(), print!(), and println!(), except they allow arbitrary expressions in placeholders. such as:

fn factorial(n: u64) -> u64 {
    if n == 0 {
        1
    } else {
        n * factorial(n - 1)
    }
}

let s = formats!("the factorial of 5 is {factorial(5)}");
prints!("the size of i32 is {std::mem::size_of::<i32>()}");
printlns!("the first 10 numbers are {(0..10).collect::<Vec<i32>>():?}");