The XLISP family

XLISP is a family of multi-platform LISP implementations, they comprise of a Scheme compatible interpreter (bytecode compiler for versions 3 and higher) called XLISP originally written by David Betz and he added few object oriented features to the basic Scheme language. The core runtime is written in C while the rest is implemented in XLISP itself and the program was released in to the public domain up until about version 2.1 where the license was changed. XLISP 2.1 is also the last Xlisp version to be available in an OS/2 port, although that port is called XLISP-PLUS on Hobbes.

The program was first released in 1983 as eXperimental LISP and was at the time a generic small LISP subset that was not Scheme compatible.

XLISP-PLUS

Tom Almy had ported Xlisp to OS/2 and DOS and added a Microsoft Windows and Linux version, with Xlisp 2.1 he forked the program and introduced his own version called XLISP-PLUS. It is not known if the fork was due to the licence change introduced with version 2.1 or if it is due to Almy's interest in getting more Common Lisp features working on the Xlisp system, but the original author resisted adding anything but an object system to the base Scheme specification.

XLISP-PLUS adds a host of Common Lisp features to Xlisp but also adds a huge amount of bug fixes, however changes to the original Xlisp such as the bytecode compiler that was introduced with version 3 have not been integrated in this fork. The maintainer stopped updating XLISP-PLUS in 1999 when CLisp was taken over by the Free Software Foundation since the maintainer believed that with the frequent CLisp updates, Xlisp would become "unnecessary". However, after 16 years of inactivity, Mr Almy suddenly kicked into life in early 2016 and created a new 3.05 version of XLISP-PLUS for MS Windows, Linux and Mac OSX, while neither the DOS not the OS/2 version got an update the libraries will function with the 3.04 OS/2 version, and he has also created a new Windows 3.x 16 bit version that will work under OS/2.

XLISP-STAT

A fork of Xlisp 2.1 with statistical additions.

WINTERP

WINTERP is a derivative of XLISP-PLUS 2.1 that adds widget support for UNIX like operating systems that have Motif.

Version

XLISP-PLUS

XLISP-PLUS v3.04 (1999-01-09)

Last known OS/2 version, note that the differences between 3.04 and 3.05 for other systems are primarily in the LISP portion of the code and if you download the xl305req.zip file from the XLISP-PLUS homepage you can run that version with the 3.04 version for OS/2.

XLISP-PLUS v3.05 (2016-02-19)
XLISP-PLUS v2.1gce (1998-05-28) - Last known Palm Pilot version.

XLISP

XLisp v2.1 (1995/12/27)
Xlisp v3 (1997 - some trivial bug fixes in 1998 and 2002)

Only released in a version for Microsoft Windows

Links

Publications

Ernst D. Schmitter: Praktische Einführung in LISP. - 1987 - Hofacker - ISBN 3-88963-229-7
Jan de Leeuw: On Abandoning XLISP-STAT - 2005 - In PDF format.

Licence and availability

Open source software
Xlisp version 2.1 and later are released under the Four Clause BSD Licence, versions prior to that are in the public domain.
XLISP-PLUS in mainly in the public domain, however a few of the included LISP library files have a no commercial usage clause.

Author

David Betz - Original Xlisp author
Tom Almy Original porter of Xlisp to OS/2, maintainer of XLISP-PLUS