Macro noders::rec

macro_rules! rec {
    (@mkstruct (
        [$firstlet:ident, $($letter:ident),*],
        { }
    ) -> ([$($letter_out:ident),*], {$($id_out:ident : $val_out:expr),*})) => { ... };
    (@mkstruct (
        [ $letter0:ident, $($letter:ident),* ],
        { $id0:ident : $val0:expr $(,$id:ident : $val:expr)* }
    ) -> ([ $($letter_out:ident),* ], { $($id_out:ident : $val_out:expr),* })) => { ... };
    { $($id:ident : $val:expr),+ } => { ... };
}