Comment by kd0amg

Writing a lisp interpreter in J won't really do more to help explore J's syntax than writing anything else in J. It might be a good way to explore how J handles tree-like data, but that's not really something J is designed to do well (if you really want to use an array-oriented language for tree processing, Aaron Hsu's dissertation covers a range of techniques that are more scalable than the naïve nest-of-short-boxed-vectors approach typically used in J).