Constructing Compilers in a persistent environment

Traditionally compilers have been described as consisting of separate modules: the syntax analyser; lexical analyser; code generator etc. However, in practice modern compilers are rarely constructed in this manner. This may be because it is difficult to find the correct levels of abstraction necessary to build a compiler from components without losing efficiency. In this paper a set of modules are described which may be combined in various ways to provide a whole family of compilers. The family of compilers includes: batch compilers; interactive compilers; file based compilers and compilers that operate entirely within the persistent environment. The approach taken is that of plug-in components. The system facilitates language and architecture experiments by providing a framework in which modules may be interchanged and combined freely.