I wrote about getting Emacs and SLIME to play nice with both Clojure and Common Lisp a while ago, but that post had a kind of hacky setup that likely doesn’t work any more.

The good news is that if you want to hack Clojure and Common Lisp with SLIME, on the same Emacs installation, this is now a lot easier to set up. First, clone this frozen copy of SLIME and load it in your Emacs init file with this snippet. Don’t use the ELPA/package.el/Marmalade SLIME as that won’t work with Common Lisp.

For Clojure, install Leiningen (or Cake), and the swank plugin. Now you can run a swank server with Leiningen (or Cake) projects with lein swank (or cake swank) and connect to it with M-x slime-connect. I had issues with threads getting stuck or deadlocked or something, but this wasn’t an issue after I installed the clojure-swank version 1.3.1. You can test this by running the ant sim demo and checking that the ants do indeed go scurrying around.

For Common Lisp, make sure your inferior-lisp-program is set to your implementation, and just use M-x slime. You can even run them at the same time without any problems, as far as I can tell.

References:

Phil H’s great work and recent blogpost on clojure-jack-in (Note that if you follow those instructions I think this will should still work, although you might not be able to run them side by side.)

Sam Aaron’s Overtone screencast is where I found out about this frozen copy of SLIME.