Semantic Subtyping for Objects and Classes

Abstract

There are two approaches for defining subtyping relations: the syntactic and the semantic one. In the semantic approach one starts from a model of the language of interest and an interpretation of types as subsets of the model. The subtyping relation is then defined as inclusion of sets denoting types. An orthogonal issue, typical of object-oriented languages, is the issue of nominal vs. structural subtyping. We aim to integrate structural subtyping with boolean connectives and semantic subtyping for a object-oriented core language and define a Java-like programming platform that exploits the benefits of both approaches, expressible in terms of code reuse and of compactness of program writing