But will an LLM write dense Common Lisp? A lot of that density comes from well-designed domain-specific macros. An LLM will have no incentive to write these on its own, though it could if a human prods it sufficiently.
Yes, human direction will still be required for the foreseeable future (whatever that means in this fast-paced field) to recognize where introducing a DSL or a macro makes sense.
They don't write dense Python. I'll tell you that. The individual functions might look good, but there's just so much repeated or nearly repeated code.
The only issue have faced with generating Lisp/scheme code, especially on small models, is that it always misses some closing parenthesis. However, because the small core language, you can use structured output in the LLMs that support it and it works quite well.