Visual programming for transputer systems

The techniques of visual programming, in which programs are constructed using graphical representations, have much to offer concurrency. This thesis reports on work performed during the development of the visual programming language, GILT (Graphical Language for Transputers). GILT uses a mixed text-graphics paradigm to aid the parallel programming process. It is strongly hierarchical and mixes visualisations of Occam style processes, inter-process communication and control flow to yield new representations of concurrent programming structures. GILTs syntax is fully defined using graph grammars and extended BNF, which together provide a new syntactic formalism for visual languages which have a mixed text-graphics model. To support the production of GILT programs, a prototype environment has been developed. The environment, which has been developed on a Sun workstation, consists of a program editor and a compiler within an integrated runtime environment. The editor has been constructed using standard user interface components and it is shown that such components are well suited to the rapid prototyping of visual languages. GILT’S compiler uses a graph reduction principle which is applicable to other visual languages and produces Occam as its output. Parallel programming is a significantly complex matter for which definitive solutions will not be produced in the near future. This thesis therefore concentrates on the development of a unified set of techniques for the production of visual languages which are aimed at easing the problems of parallel programming