A system for program refinement

Abstract

The Program Development System (PDS) is a programming environment, an integrated collection of interactive tools that support the process of program definition, testing, and maintenance. The PDS is intended to aid the development of large programs, especially program families whose members must be maintained in synchrony. The system facilitates implementation by stepwise refinement, and it keeps a refinement history that allows program modifications made at a high level of abstraction to be reflected efficiently and automatically in the corresponding low level code. Analysis tools are used both to support program validation and to guide program refinement.We describe the PDS and the tools incorporated in it, and we conclude with an example of its use.