Extending Prolog with Modularity, Concurrency and Meta-Rules

This paper presents the main features of an extension to Prolog toward modularity and concurrency—calledCommunicating Prolog Units (CPU)—whose main aim is to allow logic programming to be used as an effective tool for system programming and prototyping. While Prolog supports only a single set of clauses and sequential computations, CPU allows programmers to define different theories (P-unis) and parallel processes interacting via P-units, according to a model very similar to Linda’s generative communication. The possibility of expressingmeta-rules to specify where and how object-level (sub)golas have to be proved, not only enhances modularity, but also increases the expressive power and flexibility of CPU systems.