Macro t

macro_rules! t {
    ($id:expr, $( $name:ident : $value:expr ),* ) => { ... };
    ($id:expr ) => { ... };
}

Translate message from key, panic! if id not found…

let name = "Avery Gigglesworth";
let hi = t!("hello", name: {name});
assert_eq!(hi, "Hello, Avery Gigglesworth");