I met a coder, who has several self made programming languages, and I would never allow him anywhere near any codebases for which I'm responsible. So writing a Lisp dialect, is not something which makes you a good coder for sure. Even as a junior you can do that. Making it good, and be able to really reason for choices is a different story. I've never seen any good new reasoning from Graham like for example how Dan Abramov do all the time. They are not even close, and definitely not in favor of Graham.