Objects and Classes in Algol-Like Languages

AbstractMany object-oriented languages used in practice descend from Algol. With this motivation, we study the theoretical issues underlying such languages via the theory of Algol-like languages. It is shown that the basic framework of this theory extends cleanly and elegantly to the concepts of objects and classes. Moreover, a clear correspondence emerges between classes and abstract data types, whose theory corresponds to that of existential types. Equational and Hoare-like reasoning methods and relational parametricity provide powerful formal tools for reasoning about Algol-like object-oriented programs