[](https://gitlab.common-lisp.net/cmucl/cmucl/commits/master) CMUCL is a free, high performance implementation of the Common Lisp programming language which runs on most major Unix platforms. It mainly conforms to the ANSI Common Lisp standard. CMUCL provides a sophisticated native code compiler; a powerful foreign function interface; an implementation of CLOS; the Common Lisp Object System; which includes multimethods; a metaobject protocol; a source-level debugger and code profiler; and an Emacs-like editor implemented in Common Lisp. CMUCL is maintained by a team of volunteers collaborating over the Internet, and is mostly in the public domain. Here is a summary of its main features: * support for **static arrays** that are never moved by GC but are properly removed when no longer referenced. * **Unicode** support, including many of the most common external formats such as UTF-8 and support for handling Unix, DOS, and Mac end-of-line schemes. * native **double-double floats** including complex double-double floats and specialized arrays for double-double floats and and complex double-double floats that give approximately 106 bits (32 digits) of precision. * a **sophisticated native-code compiler** which is capable of powerful type inferences, and generates code competitive in speed with C compilers. * **generational garbage collection** on all supported architectures. * **multiprocessing capability** on the x86 ports. * a foreign function interface which allows interfacing with C code and system libraries, including shared libraries on most platforms, and direct access to Unix system calls. * support for interprocess communication and remote procedure calls. * an implementation of CLOS, the [Common Lisp Object System](http://en.wikipedia.org/wiki/Common_Lisp_Object_System), which includes multimethods and a metaobject protocol. * a graphical source-level debugger using a Motif interface, and a code profiler. * an interface to the X11 Window System (CLX), and a sophisticated graphical widget library ([Garnet](https://www.cs.cmu.edu/~garnet/), available separately). * programmer-extensible input and output streams ([Gray Streams](http://www.nhplace.com/kent/CL/Issues/stream-definition-by-user.html) and [simple-streams](http://www.franz.com/support/documentation/current/doc/streams.htm)). * an Emacs-like editor, [Hemlock](http://cmucl.org/hemlock/index.html), implemented in Common Lisp. * **freely redistributable**: free, with full source code (most of which is in the public domain) and no strings attached (and no warranty). Like the GNU/Linux and *BSD operating systems, CMUCL is maintained and improved by a team of volunteers collaborating over the Internet. For the latest news and other information, see [the wiki](https://gitlab.common-lisp.net/cmucl/cmucl/wikis/home).