Programming Paradigms as Object Classes: A Structuring Mechanism for Multiparadigm Programming

The word paradigm, is used in computer science to talk about a family of notations, that share a common way for describing program implementations. Since each paradigm is well suited for solving only a range of problems, ideally a large system should be subdivided into components, each of which should be implemented in the most appropriate paradigm. Multiparadigm programming, allows the programmer to implement a system, in a number of different paradigms. The use of multiparadigm programming techniques, could lower implementation costs, and result in more reliable and efficient applications. The difficulties that arise with multiparadigm programming can be separated into the areas of application development in multiple paradigms, design and implementation of multiparadigm environment, and generators for creating such environments. We propose the use of object-oriented design techniques as a method for encapsulating programming paradigms within multiparadigm applications, and for abstracting common characteristics across paradigms. These techniques can be used to design practical multiparadigm environment generators, and implement multiparadigm programming environments supporting a wide variety of paradigms. In order to demonstrate the validity of our approach, we describe the design and implementation of three prototypes: one in each problem area. The integrator is a multiparadigm application dealing with the numeric and symbolic evaluation of integrals. The symbolic evaluation is based on the backtracking resolution mechanism offered by the logic programming paradigm, and the numeric evaluation, on the infinite streams implemented in the functional paradigm. Additionally, lexical analysis of the input expressions is described using regular expressions, and the expression grammar is described using a BNF syntax. Finally, expression simplification uses a term rewrite system, and graphing of functions is done by directly interacting with Unix tools. Integrator is implemented in the blueprint multiparadigm programming environment, a prototype implementation of the six paradigms based on our object-oriented approach. Many different implementation techniques have been applied in order to demonstrate the wide applicability of our approach. Some of the paradigms are implemented as compilers (using existing implementations where possible), and others are implemented as interpreters. Finally, the implementation of blueprint is based on the MPSS multiparadigm environment generator. This, allows the description of paradigms as object classes using paradigm description files. Additionally, it provides a multiparadigm link editor, and support for incorporating existing compilers into multiparadigm programming environments.