Example macro in rust-lang

example-macro.js

const VALUES_COP: &'static [i32;4] = &[50000, 20000, 10000, 2000];

// macro called cashier
macro_rules! cashier {
    () => { // without arguments
        println!("Now is necessary that you enter a quantity.");
    };
    ($($x: expr),+) => { // 1 to n arguments
        {
            let mut total: u64 = 0;
            let mut _i: usize = 0;
            $( // cycle
                let number: u64 = $x
                    .trim()
                    .parse()
                    .expect("Wanted a number");
                total = total + (number * VALUES_COP[_i] as u64); // logic of operation
                _i += 1; // "_" to omit alert of use
            )+
            println!("Current Total {:?}", &total);
        }
    };
}