What I cannot create, I do not understand.

Just because you've implemented something, doesn't mean you understand it.

Setting up Emacs for Lisp hacking on OS X, pt. 2: Common Lisp and Clojure

This is likely out of date. You probably don’t want to follow these instructions. This is what I’m using now:


I updated this after using it for a while and finding out that there are problems using the most recent CVS snapshot SLIME with swank-clojure, and then after trying to answer someone’s question about this problem over on StackOverflow

These are the rest of my notes for setting up Lisp hacking on OS X, focusing on using SLIME with Common Lisp and Clojure. I’m using SBCL and Emacs from Homebrew with --cocoa. I have no idea if this will work with other Common Lisp implementations or with Aquamacs.

What seems to be the recommended way to use SLIME with Common Lisp is to use the most recent version from CVS. However, swank-clojure only works with the SLIME package in ELPA (according to this discussion on the swank-clojure Github page). And this version from ELPA is stripped down and won’t work with Common Lisp.

In order to use SLIME with both Common Lisp and Clojure in a single Emacs (and change from one to the other after restarting Emacs, but without fiddling with settings in .emacs) I had to resort to a bit of a hack.

These are the steps I did to get this to work:

With a fresh Emacs (no configuration at all, so move ~/.emacs and ~/.emacs.d somewhere else for the moment) install ELPA:


From within Emacs, install the packages “slime” and “slime-repl”. (M-x package-list-packages then C-s slime then i to select and x to install)

Move the files in ~/.emacs.d/elpa/slime-20100404 and ~/.emacs.d/elpa/slime-repl-20100404 to a new directory like ~/hacking/lisp/elpa-slime.

Throw out the ELPA install: $ rm -rf .emacs.d.

Now clone the emacs-starter-kit and move it to .emacs.d. I only did this with a fresh copy from technomancy’s Github, so try that first if you have problems.

(If you want to use Scheme too, and have followed the instructions in part 1, just save your username.el somewhere and add the two functions below once you get Common Lisp and Clojure working. You should be able to have all three set up in the same Emacs, although not running at the same time)

Get the latest SLIME with CVS:

cvs -d :pserver:anonymous:[email protected]:/project/slime/cvsroot co slime

OS X doesn’t come with CVS, but it’s installed along with XCode and the developer tools from Apple, so it might be installed on your system already.

I moved slime to ~/hacking/lisp/cvs-slime.

Hopefully it’s obvious what the Emacs Lisp below does:

(defun slime-common-lisp ()
          (setq inferior-lisp-program "/usr/local/bin/sbcl") ; your Common Lisp impl
          (add-to-list 'load-path "~/hacking/lisp/cvs-slime/")  ; your SLIME from CVS directory
          (require 'slime)
          (slime-setup '(slime-repl))

          (defun slime-clojure ()
          (add-to-list 'load-path "~/hacking/lisp/elpa-slime")
          (require 'slime)
          (slime-setup '(slime-repl))
          (slime-connect "localhost" 4005))

Now M-x slime-common-lisp will start the Common Lisp runtime and give you a SLIME REPL.

For Clojure you’d have to start the Clojure runtime and swank-clojure on port 4005, Leiningen comes with a utility for this:

$ ~/.lein/bin/swank-clojure

You can also create a new Leiningen project and start a swank-clojure inside that, but if you just want a vanilla REPL to send code to from Emacs, the above works.

Then in Emacs: M-x slime-clojure. You should now have a new buffer with a Clojure REPL with the prompt user>. Remember that you have to restart Emacs if you want to switch from one to the other. If someone knows how to avoid this, please let me know (you’d have to unload SLIME and reload the one that works with the language you want).