Dr Christopher (Tools of Computing) wrote some docs on parsing that were interesting to me (first time I saw matrix multiplication used in computing first/follow, etc sets). I am pretty sure he used Icon, because it was my first exposure to that as well. I thought it was an interesting language at the time, but never did anything with it. Good grief that was closing in on 20 years ago... sigh.

edit: found his docs on the Icon language:

https://www.tools-of-computing.com/tc/CS/iconprog.pdf