A far more sane approach, if you want to have this kind of API, is to use a PARSEC inspired parser combinator library instead, such as, for instance: https://g

A far more sane approach, if you want to have this kind of API, is to use a PARSEC inspired parser combinator library instead, such as, for instance: https://github.com/jneen/parsimmon https://github.com/jneen/parsimmon