Common lisp (especially if it had quicklisp) would be amazing, and very appropriate for a site called REPL :-)
This would be cool to have on here. I would play around with lisp a lot more if it was on my favorite programming platform
quicklisp support would be a must
imagine hacking up a quick common lisp program and deploying a production container!
and if they add autocomplete from the hyperspec ... game over!
Common Lisp has the (almost) original REPL!
@stylewarning: indeed. It deserves its own section on the website or something. :-)