GCL
GNU Common Lisp (GCL) is a Common Lisp implementation of the KCL Family that uses gcc to compile Lisp into native binaries. GCL started out as a CLtL1-level CL; steady progress is being made towards bringing it to ANSI CL compliance: It is almost there now. CVS head is rather close to compliance.

GCL is released under the terms of the LGPL and is the official common lisp of the GNU System. It runs on twelve GNU/Linux architectures (x86 amd64 powerpc s390 sparc arm alpha ia64 hppa m68k mips mipsel), Windows, Sparc Solaris, FreeBSD, and Mac OS X. GCL has support for cross-platform graphical user interfaces using the Tk widget set.

GCL is closely associated with the Maxima, ACL, ACL2, and Axiom projects.

GCL does not appear to be under active development: the last version was released in August 2005, although the developer mailing list is still active. The project is a GNU Savannah project.

The current stable release of GCL (as of 12 August 2005) is 2.6.7, and can be downloaded from GNU's FTP site. You can check out the CVS source tree using the following commands:

export CVS_RSH=ssh
export CVSROOT=:ext:anoncvs@subversions.gnu.org:/cvsroot/gcl
cvs -z9 co -r Version_2_6_7 -d gcl-2.6.7 gcl

You can download a MS Windows executable (".exe") and get other information for using GCL with Windows here.

The official home page has release notes and describes more of GCL's features (X, MPI, flexible C FFI).