Computing with text-graphic forms

Abstract

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 [0]) from computing with (textual) symbolic expressions to computing with text-graphic forms. Like LISP, PAM acheives 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 OUTLINE notation system, and then spatially lay it out. WrittenPAM also permits definition of pattern evaluating, enabling actual computation with text-graphic forms. An evaluate function for text-graphic objects is given which can execute OUTLINE expressions. An experimental version of the PAM system has been implemented in MACLISP at the Stanford Artificial Intelligence Lab.