#[macro_export]
macro_rules! dbg {
    ($expr:expr) => (dbg!("{:#?}", $expr));
	($fmt:expr, $expr:expr$(, $opt:expr)*) => {
		match $expr {
            expr => {
                eprintln!(concat!("[{}:{}] {} = ", $fmt), file!(), line!(), stringify!($expr), &expr$(, $opt)*);
                expr
            }
        }
    }
}

fn main() {
    let t = dbg!(2 + 1);
    // instead of this:
    let _: u64 = dbg!((1 << 63) | (t << 8));

    // this gives a nicer representation:
    let _: u64 = dbg!("0x{:x}", (1 << 63) | (t << 8));

    // this is also possible:
    let _: u64 = dbg!("0x{:x} with {}", (1 << 63) | (t << 8), t);
}