Algorithmic Abstraction in Object-Oriented Languages

The abstraction gap between algorithms and procedures causes numerous duplicate eeorts in implementing the same algorithms as well as apparent under-use of many eecient algorithms. A solution to this problem is to realize algorithmic abstraction at the programming language level in addition to data abstraction. In this paper, we rst discuss the two conditions for a programming language to support algorithmic abstraction. We introduce a type system, which consists of entities from a four-level hierarchy: objects, classes, types, and kinds. We also introduce a new form of parametric polymorphism, called kind-bounded parametric polymorphism, which is a generalization of universal and inclusion-bounded parametric poly-morphisms. Then we describe the KC programming language which we have designed and implemented to realize the above ideas. We predict that the introduction of algorithmic abstraction into object-oriented languages (OOLs) will greatly increase the reusability as well as the reliability of software.