monster::mutate!

macro_rules! mutate {
    (|$var:ident| $code:expr) => { ... };
    (|$($var:ident),+| $code:expr) => { ... };
}

Temporarily rebind variables as mutable

Example

#[macro_use(mutate)]
extern crate monster;

fn main() {
    let x = 42;
    let y = 777;

    mutate!(|x, y| {
        x += 1;
        y += 1;
    });

    println!("{}, {}", x, y);
}