IMPLEMENTATION OF LANGUAGE ENHANCEMENTS*

Abstract--Data abstractions have been proposed as a mean,, to enhance program modularity. The implementation of such ne ~ features to an existing language is typically handled bx either rewriting large portions of an existing compiler or by using a preprocessor 1o translate the extensions into the standard language. The first technique is expensixe to implement while the latter is usuall 3 slov, and clumsy to use. In this paper a data abstraction addition to PL 1> described and a hybrid implementation is gixen. A minimal set of primitive features are added to the compiler and the other extensions are added via an internal macro processor that expand, the ne ~ syntax inlo the existing language. Compiler design Data abstraction Language extensions Specifications 1