Formalization and ´literate´ programming

The ´literate´ programming model is extended to include a concept of mechanical transformation. A prototype tool, FLP (formal literate programming tool), has been developed which uses this extended ´literate´ programming model in both a formal program proof setting, and within a formal (refinement) program development setting. In both settings, FLP provides history, access to tools, and an easy-to-use interface. FLP is a system with (i) a tree structured revision control system allowing easy access to an entire software development history, (ii) a unifying semi-formal model encompassing both program proof and refinement, and (iii) a single simple mechanism for managing both formal transformations on programs (proofs, tests, refinements) and informal transformations (explanations). In this paper, we outline the underlying semi-formal model for this extended ´literate´ programming tool, briefly show the system architecture, and demonstrate the tool´s use during a sample program development.