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About Clozure CL

Clozure CL is an open source Common Lisp implementation that runs on PowerPC hardware under Mac OS X and LinuxPPC, and on x86-64 hardware under Linux, Mac OS X, and FreeBSD. A port to 32-bit x86 is progressing well; a port to 64-bit Windows is also pretty far along.

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.

Getting Clozure CL

Current snapshots of CCL are available via anonymous ftp at

The most recent snapshot release is from July 2007; there has been a lot of activity since then. Therefore, once you have the snapshot installed and running, you'll probably want to update from sources. See UpdatingFromSource (for CVS users) and UpdateFromSubversion for instructions on how to do that.

Version 1.2-rc1

Archives of release candidate 1 of Clozure CL 1.2 are avalable via anonymous ftp at


The Clozure CL manual is available on the web at As of Clozure CL 1.2, the DocBook sources for the manual are included with the distribution.

Mailing Lists

There are two CCL-related mailing lists hosted at These lists are managed with GNU Mailman software, which provides a simple web-based interface for managing subscription options.

Support and Consulting

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

In-Depth CCL

Orient Yourself to Clozure CL Culture