Macro orderable 

macro_rules! orderable {
    (@transform []) => { ... };
    (@transform [*]) => { ... };
    (
        $(#[$meta:meta])*
        $vis:vis struct $name:ident {
            $(
                $(#[$field:meta])*
                $var:ident: $t:ty$([$tt:tt])?$(,)?
            )+
        }
    ) => { ... };
}