[librasteve]

recommend you check out raku Grammars … https://docs.raku.org/language/grammars

[draegtun]

Or in Red's case, Parse - https://www.red-lang.org/2013/11/041-introducing-parse.html

[binary132]

There’s really nothing about this that couldn’t be expressed just as clearly in a more general API though, even in C, IMO. Building it into the syntax is a little weird to me.