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Lisp at TWENEX.ORG Tutorial

Lisp is a programming language famous for its use in Artificial Intelligence and advanced Computer Science research. First developed in 1958, it is the second oldest (after Fortran) high-level programming language still in common use.

Two dialects of Lisp are available at TWENEX.ORG, Maclisp and InterLisp-10.



Maclisp was developed in the mid-1960's as part of MIT's Project MAC1), originally for the PDP-6 ITS operating system.

Maclisp was a highly influential language and was the primary inspiration for Common Lisp, with contributions form other dialects like InterLisp.


Before running MACLISP, you must define the following logical name:


(You can add the above line to your LOGIN.CMD file to automatically define the logical name for all of you TWENEX sessions.)

It is also recommended that you create a Maclisp init file (LISP.INI) in your home directory with the following contents:

;;; A very typical init file / Emacs mode--> -*- Mode:LISP; -*-
(COMMENT) ;magic
(PROGN ; real init file stuff
  (SETQ BASE 10. IBASE 10. *NOPRINT NIL) ;base-10 display
  (SETQ NOUUO T *RSET T) ;these make debugging easier
  (SSTATUS FEATURE NOLDMSG) ;supress module load messages
  '*) ;return an asterisk for Maclisp to print out


LEDIT is a software package that allows a programmer to inspect, modify, and save Lisp source expressions from within a Maclisp session, abilities Maclisp itself lacks. This is achieved by calling the Emacs editor from the programmer's Maclisp session.

To use LEDIT:

  1. Start Maclisp and load your source file.
  2. Evaluate (LOAD “LISP:LEDIT.FASL”) (You may add this line to your LISP.INI file and eliminate this step.)
  3. Evaluate (LEDIT) to switch to Emacs.
  4. Load the source file into Emacs (^X ^F).
  5. View, change, save source with Emacs commands.
  6. Flag function definitions to update in Maclisp with M-Z.
  7. Return to Maclisp with ^X Z.



InterLisp was developed in 1967 at Bolt, Beranek and Newman (BBN) for TENEX, BBN's in-house PDP-10 operating system. Development was later transfered to XEROX PARC. The language became popular with Stanford University AI researchers and at other principly US West-Coast institutions.

InterLisp was noted for its integration of interactive development tools into the the programming environment: debugger, Lisp-structure-aware editor, spelling corrector, file manager.

The dialect was in a rivalry with Maclisp prior to the development of Common Lisp.


If you have set-up your TWENEX session for Maclisp (see above), you must undefine the logical name LISP: and set @DEFINE INTERLISP PS:<INTERLISP> before running InterLisp.


for Mathematics And Computation. The name is unrelated to the later-developed Apple Macintosh computer
tutorials/lisp.txt · Last modified: 2022/03/15 05:07 by smj