Computing with Text-Graphic Forms

Fred H. Lakin*

Stanford Artificial Intelligence Laboratory

Computing with text graphic forms occurs when text graphic patterns are used to direct the processing of other text graphic patterns. The PAM graphics system was designed for just this kind of computation; PAM stands for PAttern Manipulating      PAM is a generalization of LISP (McCarthy 1960)** from computing with (textual) symbolic expressions to computing with text graphic forms.

Like LISP, PAM achieves processing power by providing atomic objects, means of structuring them into complex objects and taking them apart, and equality tests for objects. Text graphic engines can then be defined, allowing text editors, text graphic editors, circuit design aids and visual language processors to all be developed in the same LISP like environment. Examples discussed in the paper are:

handPAM is an agile environment for the manual manipulation of text graphic objects (described briefly).

writtenPAM provides programmatic manipulation of visual objects. Pattern processing is demonstrated by functions which translate a LISP sexpr to the visual name shape synonyms of the VennLISP notation system, and then spatially lay it out.

writtenPAM also permits definition of pattern evaluating, enabling actual computation with text graphic forms. An eval function for text graphic objects is given which can execute VennLISP expressions.

An experimental version of the PAM system has been implemented in MACLISP at the Stanford Artificial Intelligence Lab.***

Definition of the member function in the VennLISP dialect


Evaluation of visual mapping function with underlying tree structure shown



A Structure from Manipulation for Text Graphic Objects

Basic Functions of writtenPAM

Predicates of writtenPAM

Text Graphic Pattern Notation

Pattern Processing

Pattern Evaluating

The function vizeval

Notes on the Illustrations



This paper was published in the proceedings of the first-ever LISP Conference at Stanford University, August 1980.

* at the time visiting Xerox Palo Alto Science Center, 3333 Coyote Hill Road, Palo Alto, CA 94304

** McCarthy, John, "Recursive functions of symbolic expressions and their computation by machine", Comm. ACM, 1960, vol. 3, no.4.

***And a production version called "vmacs" is now in daily use, running in CMUCL under OS X, and was used to create this html version.

Return to papers list

© 1980, 1994, 2009 PGC