Actually, I've been working with getting grammars for binary data working in Raku. Development paused though when I had some trouble working with slangs.
Definitely read over the proposal and comments, as my work with binary formats is a drop the bucket of ways to work with them, and I'm always interested in hearing how others would need/use such a feature.
I've gotten a bit better with them since then, but now I'm holding off for RakuAST, else I'd probably be rewriting a large amount of code for nothing (or have some major performance hits). You can see the proposal at https://gist.github.com/alabamenhu/2fec7a8f51a24091dc1b104a2... and a very early implementation at https://github.com/alabamenhu/BinexObjex
Definitely read over the proposal and comments, as my work with binary formats is a drop the bucket of ways to work with them, and I'm always interested in hearing how others would need/use such a feature.