Swank/slime support for clojure
Clojure Emacs Lisp
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Swank Clojure

Swank-clojure is an adapter that lets you use SLIME (the Superior Lisp Interaction Mode for Emacs) with Clojure. It's designed to work with GNU Emacs 23 and higher. It may work with forks like XEmacs/Aquamacs or earlier versions of Emacs, but those are not as well supported.


Depending on what you're using it for, Swank Clojure can be invoked in a few different ways:

  1. Standalone Session: If you just hit M-x slime, swank-clojure will download the jars for Clojure, contrib, and swank-clojure, launch an instance, and connect to it. If you just want to try out Clojure, this is all you need. Just get Swank Clojure through ELPA and stop reading here. =)

  2. Custom classpath: If you want to hack on Clojure or Contrib, set swank-clojure-classpath to a list of paths to the jars you want to use and then hit M-x slime.

  3. Project: Put your project's dependencies in the lib/ directory, (either manually or using Leiningen or Maven) then launch M-x swank-clojure-project. Note that you must have swank-clojure.jar in the lib/ directory, it will not automatically add itself to the classpath as it did in past versions that had to run from a checkout.

  4. Standalone Server: Users of Leiningen or clojure-maven-plugin can launch a server from a shell and connect to it from within Emacs using M-x slime-connect.

Because the JVM classpath can't be modified at runtime, you can't start a session with plain M-x slime and then decide to work on your project; you'll need to start a new slime session with M-x swank-clojure-project.


Install from ELPA using package.el[1].

When you perform the installation, you will see warnings related to the byte-compilation of the packages. This is normal; the packages will work just fine even if there are problems compiling it upon installation.

If you're only going to use #4 above, you'll only need the "slime-repl" package. Otherwise get the "swank-clojure" package.

While it's possible to install swank-clojure manually, it's not recommended. ELPA will be included in the next version of Emacs and has been a standard piece of the Emacs ecosystem for a while now. See the "Installing from Source" section below if you wish to hack on a development version that hasn't been released yet.

Be sure you don't have old versions of SLIME either manually installed or installed using a system-wide package manager like apt-get. If you do have any manual configuration of SLIME, be sure to place it after package.el is initialized.

Project Layout

If you intend to use M-x swank-clojure-project, it will prompt for a project dir and set up the classpath for that structure based on some existing Clojure conventions:

  • src/, classes/, and test/ - added to the classpath
  • lib/ - all .jars in here are added to the classpath
  • src/main/clojure, src/test/, target/classes, target/dependency - added if pom.xml exists (maven-style) All jars in target/dependency will be added as well.

Your project should include all its dependent jars (including Clojure and Swank-Clojure) in either lib/ or target/dependency. If it depends on more than just Clojure, Contrib, and Swank, it's recommended that you use a dependency manager such as Leiningen to manage these.

If you have a running session and you add jars to lib/, you need to start a new session. Invoke M-x swank-clojure-project to get a session with the new classpath in place. M-x slime-restart-inferior-lisp will restart the subprocess, but it does not recalculate the classpath.


You can embed swank in your project, start the server from within your own code, and connect via Emacs to that instance:

(ns my-app
  (:use [swank.swank :as swank]))
(swank/start-repl) ;; optionally takes a port argument

Then use M-x slime-connect to connect from within Emacs.

You can also start the server directly from the "java" command-line launcher if you AOT-compile it and specify "swank.swank" as your main class.


Commonly-used SLIME commands:

  • M-TAB: Autocomplete symbol at point
  • C-x C-e: Eval the form under the point
  • C-c C-k: Compile the current buffer
  • M-.: Jump to the definition of a var
  • C-c S-i: Inspect a value
  • C-c C-m: Macroexpand the call under the point
  • C-c C-d C-d: Look up documentation for a var
  • C-c C-z: Switch from a Clojure buffer to the repl buffer
  • C-c M-p: Switch the repl namespace to match the current buffer

Pressing "v" on a stack trace a debug buffer will jump to the file and line referenced by that frame if possible.

Note that Slime was designed to work with Common Lisp, which has a distinction between interpreted code and compiled code. Clojure has no such distinction, but many of the Slime commands retain parallel load/compile commands that have the same effect in the context of Clojure.

Keeping Common Lisp

If you want to use SLIME with Common Lisp or another Lisp implementation, add this to your Emacs config:

(add-to-list 'slime-lisp-implementations '(sbcl ("sbcl")))

Then launch Slime with M-- M-x slime $LISP instead of just M-x slime.


The mailing list and clojure channel on Freenode are the best places to bring up questions/issues.

Contributions are preferred as either Github pull requests or using "git format-patch" as is requested for contributing to Clojure itself. Please use standard indentation with no tabs, trailing whitespace, or lines longer than 80 columns. If you've got some time on your hands, reading this style guide wouldn't hurt either.

Installing from Source

Swank-clojure is really two pieces: a server written in Clojure and a launcher written in Elisp. The elisp parts are installed with:

$ git clone git://github.com/technomancy/slime.git
$ git clone git://github.com/technomancy/clojure-mode.git

Open slime/slime.el, slime/contrib/slime-repl.el, clojure-mode/clojure-mode.el, and swank-clojure.el and hit M-x package-install-from-buffer in each buffer in order. You will get compiler warnings, but they should not be fatal. Restart Emacs, and you should be able to use M-x slime.

The Clojure-side server is managed with Leiningen. Use the "lein install" task to place it in your local repository.

Note that using Slime from CVS trunk is not recommended; changes have been introduced which are incompatible with the current implementation of the Clojure server. Using the versions in git from above will ensure that you have a compatible version.


Copyright (C) 2008-2009 Jeffrey Chu, Phil Hagelberg

This file is licensed under the terms of the GNU General Public License as distributed with Emacs (press C-h C-c to view it).

[1] - ELPA is the Emacs Lisp Package Archive. It brings a real package manager to Emacs.