Logic program development based on typed moded schemata and data types

The main contribution of the thesis is to develop a comprehensive framework for developinglogic programs using ve program schemata and some basic data types, and to evaluate itssuitability for developing sizable programs. The schemata are intended to capture designdecisions made by a programmer during top-down re nement of a predicate. The schemataare completely independent from the data types, and have associated types and modes. Themethod of construction is to start from an initial typed moded call, and proceed using pre-cisely de ned re nement operations until primitive data type operations are introduced. It isshown that the construction method produces programs that are polymorphic many-sortedformulas, and that computations using the programs cannot result in type or mode errors.The framework is compared with previous schema-based program development methodsfrom the literature, and we argue that this method is better suited to the development ofnon-trivial programs, and is more amenable to computerised support. The introductionof types and modes into schemata is a signi cant addition, not previously reported. Anapproach to program veri cation is also introduced, in which the proof of correctness of aprogram is built from proof schemata corresponding to the program schemata used in thedesign of the program. Finally an implementation of the system is described and its useis illustrated on some sizable programs. The implementation incorporates a static analysisalgorithm for checking the validity of the modes during the development of the program.