I've found LLMs to be bad at balancing parenthesis. I've also found them to be less likely to hallucinate library types in dynamic languages, they tend to hallucinate arguments to library functions/methods instead.
Because you treating Lisp just like any other (non-homoiconic) PL. Give an agent a true Lisp REPL to mess around, and you'd be surprised. Things get very interesting. I still don't understand why more people don't do that - isn't that obvious first thing anyone should figure out? Like I can't even imagine working with Lisp without a REPL and structural editing - I'd immediately fail at balancing parens. Why do you expect a [dumber] machine would do any better?
What do you think about making the agent write type annotations? There are built-in forms in CL, and in Smalltalk, I settled for pragmas for now. They are not checked, but since I started using them, I think the rate of one- or two-shotting solutions has gone up.
I think that was true last year. In my experience, it’s no longer the case with Claude Code or Codex.