AUCS / TR9116 Two-dimensional Visual Programming and Three-dimensional Execution Visualisation in Prolog

This report is a highly compressed review of some of the basic ideas in a formalism for visual programming and visualisation of program execution in Prolog. Some previously unreported refinements of the formalism are illustrated. A new, simple, expressively complete visual formalism for programming in Prolog is presented. The formalism is noted to be equivalent to the standard textual notation for Prolog. Some aspects of Prolog programs are identified that appear to be clearer for novices when presented in the graphic formalism, while other aspects of Prolog are identified that may be clearer in the standard textual notation. The design of an implemented computer environment dubbed VPP (short for "Visual Programming in Prolog") is outlined that supports visual programming in Prolog using the graphical formalism. Two different implemented experimental prototypes of VPP are described.