Macro arrr 

macro_rules! arrr {
    ( $array:tt as $typ:tt $(or $default:tt )? ) => { ... };
    ( @bind, [$($x:tt),*], $typ:tt ) => { ... };
    ( @bind, $x:literal, $typ:tt ) => { ... };
    ( @typ, [$type:ty; $size:expr] ) => { ... };
    ( @size, [$type:ty; $size:expr] ) => { ... };
    ( @default, $default:expr ) => { ... };
    ( @init, $typ:tt, $default:expr ) => { ... };
    ( @init, $typ:tt ) => { ... };
}