I have a pet language Inm love because LLMs have shown themselves to be quite lousy at writing it. It makes programming a lot more fun when you have to do it yourself.

I mean, it can still reason about it, but the code it (Claude and Gemini) frequently doesn't compile and it throws edits onto it until it does. When it then compiles this pretty much c# written in a functional HM-typed sexpr language that lacks classes.

AI has been great help in writing the compiler, though. I got stuck in codegen after having written a lexer, parser and type checker, and not only did it make a faster and better code generator than I ever could, it also made the type checker about 5x fater.