Version 103 (modified by gb, 11 years ago) (diff)


About Clozure CL

Clozure CL is a free Common Lisp implementation that runs on the following platforms:

  • Mac OS X 10.4 and later (PowerPC and x86)
  • Linux (PowerPC and x86)
  • FreeBSD 6.x and later (x86)
  • Solaris (x86)
  • Microsoft Windows (x86)

There are both 32- and 64-bit versions for all platforms.

Some distinguishing features of the implementation include:

  • fast compilation speed
  • native OS threads
  • precise, generational, compacting garbage collector
  • convenient foreign-function interface

Clozure CL used to be called OpenMCL. It is also sometimes called CCL. You will see the three names being used interchangeably.

See SystemRequirements for hardware and software requirements.

Getting Clozure CL

The most recent released version of Clozure CL is version 1.3.

The preferred way to get Clozure CL is via Subversion. For example, to get Clozure CL 1.3 for Darwin/x86, you'd type (where the $ is the shell prompt):

$ svn co

You can get versions for other platforms by changing the darwinx86 to one of linuxx86, freebsdx86, solarisx86, windows, darwinppc, or linuxppc.

Please see Obtaining, Installing, and Running Clozure CL for details on completing the installation.

If you don't have Subversion installed, you can download an archive listed in the table below. All these archives are available via anonymous ftp at

x86 PowerPC
Darwin (Mac OS X) .tar.gz (or .dmg) .tar.gz (or .dmg)
FreeBSD .tar.gz
Linux .tar.gz .tar.gz
Solaris .tar.gz
Windows .zip

After installing CCL, read about getting updates and bug fixes.


The Clozure CL manual is available as a single web page at or as multiple pages at As of Clozure CL 1.2, the DocBook sources for the manual are included with the distribution.

We have started to collect a list of FrequentlyAskedQuestions.


Mailing Lists

There are two CCL-related mailing lists hosted at Click on a list's link to subscribe or to view archived messages.


Everyone interested in Clozure CL is welcome to participate in #ccl on The channel logs are available. We also keep logs for #lisp and logs for #scheme.

Paid Support

Clozure Associates provides commercial support and consulting services for Clozure CL as well as other Common Lisp implementations. These services can range from helping you debug your software to adding extensions to CCL, to providing several full time Lisp programmers to help you build your application. Please contact us at business@… for more information.

Starting Points

CCL Basics

Contributing to CCL

In-Depth CCL

Orient Yourself to Clozure CL Culture

This site

This site allows any registered user to add and modify wiki pages and "tickets" (bug reports.) Registration has traditionally been a simple matter of clicking on a link (in the upper right of each page), filling out a web form to give yourself a user name and password, and clicking the OK button; that simple manual step has usually been enough to deter spammers.

Unfortunately, that simple step no longer seems to be adequate, and (presumably via some automated process) spammers have been able to register for accounts here and use those accounts to ... do what they do. Until we can find a better way to ensure that real human beings are registering for accounts on this site (and neither spammers nor their automated tools would fit that description), we've disabled the "Register" link and functionality. (This shouldn't affect the ability of anyone who's already registered to log in here, but it does make it a little harder for new users to register.)

If you don't have an account on this Trac site and would like one, please send a message to "trac-register" AT ""; please include your name and a preferred user name. We'll create an account for you and send you back the login details; you should be able to log in here using that information and change your password/otherwise manage your account.)

Hopefully, we'll find a better solution (captchas, email confirmation) to this problem soon.