CMUCL is a free implementation of the Common Lisp programming language which runs on most major Unix platforms. It mainly conforms to the ANSI Common Lisp standard. 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 and 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, 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).
• programmer-extensible input and output streams.
• an Emacs-like editor 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.

Latest News

2010-08 snapshot and 20b prerelease 1

CMUCL 20b prelease 1 has been released, in preparation for the upcoming 20b release. Therefore there will not be a 2010-08 snapshot.

• Error handling has been added to external formats. Previously, all external formats would silently replace bad encodings with a suitable replacement character. Now, the user can specify how the errors are handled by using the :DECODING-ERROR and :ENCODING-ERROR parameters to OPEN. The default is the previous behavior.

  For decoding-error, a character, symbol, or function can be given. If a character, then that character is used as the replacement character. For a symbol or function, it must be a function of 3 arguments: a message string, the offending octet (or nil), and the number of octets read in the encoding. If the function returns, it must be the codepoint of the desired replacement.

  For encoding-error, a character, symbol, or function can be given. If a character, then that character is used as the replacement character. For a symbol or function, it must be a function of 2 arguments: a message string and the offending codepoint. If the function returns, it must be the codepoint of the desired replacement.

• Add EXT:LIST-ALL-EXTERNAL-FORMATS to list all known external formats and their aliases.
• ADD EXT:DESCRIBE-EXTERNAL-FORMAT to print a description of the specified exernal format. To support this, the macros DEFINE-EXTERNAL-FORMAT and DEFINE-COMPOSING-EXTERNAL-FORMAT have changed.
• The sparc port now supports the :executable feature.
• The Mac OS X port now support the :executable feature.
• A critical bug in the fast unicode stream buffering routine has been fixed. This bug manifests itself by causing valid sequences to be incorrectly decoded, resulting in a replacement character.
• UTF-8 correctly catches overlong sequences now. Previously, overlong sequences were missed.
• When UTF-8 decoder encounters an overlong sequence, a surrogate code point, or a too-large codepoint, the entire sequence is converted to the replacement character. Previously, all of the octets except the first were put back, and the data read again.
• Some GC improvements for sparc and ppc. (Changes for ppc untested). GC could incorrectly move the PC and other registers, causing a segfault.
• A bug inadvertently introduced in the 2010-04 non-unicode snapshot has been fixed. The bug prevented the non-unicode versions of CMUCL from loading the external format aliases file.
• With SSE2, the imaginary part of a (complex single-float) is now returned correctly.
• The method used to create executable images for Linux has been cleaned up and should be far more robust against different versions of the OS. The same is true on sparc as well as Mac OS X.

What is Common Lisp?

Common Lisp is well suited to large programming projects and explorative programming. The language has a dynamic semantics which distinguishes it from languages such as C and Ada. It features automatic memory management, an interactive incremental development environment, a module system, a large number of powerful data structures, a large standard library of useful functions, a sophisticated object system supporting multiple inheritance and generic functions, an exception system, user-defined types and a macro system which allows programmers to extend the language.

Pascal is for building pyramids -- imposing, breathtaking structures built by armies pushing heavy blocks into place. Lisp is for building organisms ...
Alan Perlis