AN OBJECT-ORIENTED DENOTATIONAL SEMANTICS OF A SMALL PROGRAMMING LANGUAGE

A denotational semantics of a programming language specifies the meani ng of the language in terms of well-defined mathematical structures. T o this end, state-based formal specification notations such as VDM and Z can be used to specify denotational semantics by defining the trans ition from language constructs into mathematical entities. However, wh en using such notations, the abstract syntax, static semantics and dyn amic semantics are typically defined separately using distinct formal structures. As a consequence, adding a new construct to the language u sually requires modification of each of the above structures. Furtherm ore, this traditional denotational semantic style generally has limite d modularity and reusability. This paper advocates the use of the Obje ct-Z notation to give an object-oriented specification of programming language semantics. With this approach, programming language construct s, such as expressions and statements, are viewed as objects, with the result that the abstract syntax, static and dynamic semantics of indi vidual language constructs become encapsulated in one class. This modu larity assists readability and facilitates subsequent semantic modific ation with minimal disruption.