Abstract

. Strongly typed polymorphism is necessary for expressing safe reusable code. Two orthogonal forms of polymorphism exist: inclusion and parametric, the Oberon language only supports the former. We describe a simple extension to Oberon to support parametric polymorphism. The extension is in keeping with the Oberon language: it is simple and has an explicit cost. In the paper we motivate the need for parametric polymorphism and describe an implementation in terms of translating extended Oberon to standard Oberon. 1 Introduction A key goal of Software Engineering is to support the production and use of reusable code. Reusable code, by definition, is "generic" i.e. applicable in a number of different contexts. To guarantee that code is reused correctly strong typing is desirable. Genericity in code can best be expressed by polymorphic types. Two different forms of polymorphism have been identified: inclusion and parametric [2]. In theory inclusion and parametric polymorphism are orthogona...

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