I don't know if Lisp is to blame, but we had exactly the same thought, and I gave it a shot: https://github.com/lvh/regex-crossword https://github.com/lvh/regex

I don't know if Lisp is to blame, but we had exactly the same thought, and I gave it a shot: https://github.com/lvh/regex-crossword https://github.com/lvh/regex-crossword I did the somewhat bruteforcy generate-strings-and-learn-from-that way, instead of working off the parse tree. The latter is clearly more efficient, but also not something I can implement in <1h before work -- and it has the logic engine in the center, meaning it's not a dead end if I want to pick it up again :-)