A lambda calculus forEnhanced Strict Inheritance

M. Temperini, Dipartimento di Informatica e Sistemistica Universita' di Roma "La Sapienza"

Abstract:

We present an inheritance mechanism for a strongly typed object-oriented language, called Enhanced Strict Inheritance - ESI). It is a mechanism of classification in which subclassing relationship between classes implies subtyping relationship between the corresponding types. The definition of ESI is based on a covariant redefinition rule between methods. ESI is modeled by the $\lambda{\&}_{ESI}$-calculus, a modification of the $\lambda{\&}$-calculus of overloaded functions [CGL93]. In defining ESI hierarchies the only constraint designer has to force is covariance of attribute redefinition; so other restrictions defined in related approaches to force soundness of their type systems are relaxed. ESI approach is based on a peculiar notion of point of view for multiple inheritance, called abstraction level.