I'm finding the opposite: Claude Code is strikingly good at Common Lisp (unsurprising given how much CL material would have made it into the training set), and even much better than I expected with Arc.

However, a large part of OP is about REPLs and on that I've also had a hard time with CC. I was working on it this evening in fact, and while I got something running, it's clunky and slow.