A type classes system for logic programming

This paper describes an extension for logic programming. We propose a flexible logical language that combines overloading and higher-order polymorphism by means of a type classes system. Our proposal consists in classifying the logical predicates, collecting the set of types which share predicates with common application domains in the same type class and particularising more specific applications by the appropriate instantiation of the class. The power and expressiveness of this approach is shown by the declaration of a class of graphs which allows to comprise and solve the kind of well-known benchmarks problems in an expressive and easy way. Besides we propose a natural generalisation of type classes by by means of the concept of constructor class which constitutes a powerful extension of the system.