Macro make_fn 

macro_rules! make_fn {
    ($name:ident<$i:ty, $o:ty>, $rule:ident!($( $body:tt )* )) => { ... };
    (pub $name:ident<$i:ty, $o:ty>, $rule:ident!($( $body:tt )* )) => { ... };
    ($name:ident<$i:ty, $o:ty>, $rule:ident) => { ... };
    (pub $name:ident<$i:ty, $o:ty>, $rule:ident) => { ... };
}

Constructs a function named $name that takes an input of type $i and produces an output of type $o.

make_fn!(myrule<StrIter, &str>,
    text_token!("token")
);

You can also specify that the function is public if so desired.

make_fn!(pub otherrule<StrIter, &str>,
    text_token!("other")
);