Visual interactive production language systems

In earlier work on anticipation and prompting systems for programming languages it was recognized that a more formal approach to development of such interactions with programmers at display terminals was needed. It was observed that the bulk of the data involved in these interactions was in the displays themselves and that certain display drivers operated on action strings similar to those in production language systems. The development of special Floyd-Evans production languages oriented toward a visual interactive environment was therefore undertaken. Based on two experimental interpreters which have been implemented, the language itself has now been substantially refined and compilers for a common language have been designed with one being implemented. In the first implementation which was accomplished on a Datapoint 2200, a substantial portion of the effort was devoted to a pedagogic display of the parsing process. In the second implementation on an Interdata 85, all of the programming was made reentrant so that multiple users can be served using the same or different target languages. Furthermore, some of the basic functions were reduced to microcode, although it was not possible to carry this as far as had been hoped. It was also learned during development of the second system that left-part matching and right-part replacement could be treated as generalized actions—thus simplifying the internal structure of the interpreter. Development of these systems is part of ongoing research with programming languages and automated programmer assistance.