common-lisp OpenMCL is a Common Lisp implementation. It began as a subset of the commercial MCL (Macintosh Common Lisp), and has grown into a full-featured, stable implementation. All of OpenMCL is released under the GNU Lesser General Public License. Commercial MCL does have a nicely integrated IDE and user interface libraries, which were not open-sourced and are not available in OpenMCL. This port contains the heap image and other tools for building OpenMCL (OpenMCL needs an OpenMCL heap image to build itself).