Classifying Prototype-based Programming Languages

Abstract

The prototype-based programming model has always been diicult to characterize precisely. Prototype-based languages are all based on a similar set of basic principles, yet they all diier in their precise in-terpretation of these principles. Moreover, if the prototype-based model advocates concrete objects as the only mean to model concepts, cur-rent languages promote methodologies reintroducing abstract construc-tions to manage eeciently groups of similar objects. In the past, we have proposed two classiications of delegation-based languages in or-der to clarify these issues. In the present paper, we come back to these two classiications in the light of our recent work. The rst classiication looks at the primitives of the virtual machine underlying each language; it classiies languages according to the semantics of these primitives. The second considers the group-oriented constructions provided in each language; it classiies languages according to the level of abstractness of these constructions. The two classiications complements each others and also other existing classiications. They allow people to assess more precisely the relative merits of the diierent languages.