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Chapter 1 Introduction

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. Here is a summary of its main features:

This user's manual contains only implementation-specific information about CMUCL. Users will also need a separate manual describing the Common Lisp standard, for example the Hyperspec.

In addition to the language itself, this document describes a number of useful library modules that run in CMUCL. Hemlock, an Emacs-like text editor, is included as an integral part of the CMUCL environment. Two documents describe Hemlock: the Hemlock User's Manual, and the Hemlock Command Implementor's Manual.

1.1 Distribution and Support

CMUCL is developed and maintained by a group of volunteers who collaborate over the internet. Sources and binary releases for the various supported platforms can be obtained from These pages describe how to download by FTP or CVS.

A number of mailing lists are available for users and developers; please see the web site for more information.

1.2 Command Line Options

The command line syntax and environment is described in the lisp(1) man page in the man/man1 directory of the distribution. See also cmucl(1). Currently CMUCL accepts the following switches:

specifies batch mode, where all input is directed from standard-input. An error code of 0 is returned upon encountering an EOF and 1 otherwise.
enters quiet mode. This implies setting the variables *load-verbose*, *compile-verbose*, *compile-print*, *compile-progress*, *require-verbose* and *gc-verbose* to NIL, and disables the printing of the startup banner.
requires an argument that should be the name of a core file. Rather than using the default core file (lib/lisp.core), the specified core file is loaded.
specifies to enter Hemlock. A file to edit may be specified by placing the name of the file between the program name (usually lisp) and the first switch.
accepts one argument which should be a Lisp form to evaluate during the start up sequence. The value of the form will not be printed unless it is wrapped in a form that does output.
accepts an argument that should be the name of the hemlock init file to load the first time the function ed is invoked. The default is to load hemlock-init.object-type, or if that does not exist, hemlock-init.lisp from the user's home directory. If the file is not in the user's home directory, the full path must be specified.
accepts an argument that should be the name of an init file to load during the normal start up sequence. The default is to load init.object-type or, if that does not exist, init.lisp from the user's home directory. If the file is not in the user's home directory, the full path must be specified.
accepts no arguments and specifies that an init file should not be loaded during the normal start up sequence. Also, this switch suppresses the loading of a hemlock init file when Hemlock is started up with the -edit switch.
accepts an argument which should be the name of a file to load into Lisp before entering Lisp's read-eval-print loop.
specifies that Lisp should start up as a islave Lisp and try to connect to an editor Lisp. The name of the editor to connect to must be specified---to find the editor's name, use the Hemlock ``Accept Slave Connections'' command. The name for the editor Lisp is of the form:
where machine-name is the internet host name for the machine and socket is the decimal number of the socket to connect to.
For more details on the use of the -edit and -slave switches, see the Hemlock User's Manual.

Arguments to the above switches can be specified in one of two ways: switch=value or switch<space>value. For example, to start up the saved core file mylisp.core use either of the following two commands:

   lisp -core=mylisp.core
   lisp -core mylisp.core
1.3 Credits

CMUCL was developed at the Computer Science Department of Carnegie Mellon University. The work was a small autonomous part within the Mach microkernel-based operating system project, and started more as a tool development effort than a research project. The project started out as Spice Lisp, which provided a modern Lisp implementation for use in the CMU community. CMUCL has been under continual development since the early 1980's (concurrent with the Common Lisp standardization effort). Most of the CMU Common Lisp implementors went on to work on the Gwydion environment for Dylan. The CMU team was lead by Scott E. Fahlman, the Python compiler was written by Robert MacLachlan.

CMUCL's CLOS implementation is derived from the PCL reference implementation written an Xerox PARC. Its implementation of the LOOP macro was derived from code from Symbolics, which was derived from code written at MIT. The CLX code is copyrighted by Texas Instruments Incorporated.

CMUCL was funded by DARPA under CMU's "Research on Parallel Computing" contract. Rather than doing pure research on programming languages and environments, the emphasis was on developing practical programming tools. Sometimes this required new technology, but much of the work was in creating a Common Lisp environment that incorporates state-of-the-art features from existing systems (both Lisp and non-Lisp). Archives of the project are available online.

The project funding stopped in 1994, so support at Carnegie Mellon University has been discontinued. The project continues as a group of users and developers collaborating over the Internet. The currently active maintainers are:

In particular Paul Werkowski and Douglas Crosher completed the port for the x86 architecture for FreeBSD. Peter VanEnyde took the FreeBSD port and created a Linux version. Other people who have contributed to the development of CMUCL since 1981 are This manual is based on CMU Technical Report CMU-CS-92-161, edited by Robert A. MacLachlan, dated July 1992. Other contributors include Raymond Toy, Paul Werkowski and Eric Marsden.
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