From Standard to Non-Standard Semantics by Semantics Modifiers

An approach for systematically modifying the semantics of programming languages by semantics modifiers is described. Semantics modifiers are a class of programs that allow the development of general and reusable "semantics components". Language in- dependence is achieved through the interpretive approach: an interpreter serves as a mediator between the new language and the language for which the non-standard se- mantics was implemented. Inverse computation, equivalence transformation and neigh- borhood analysis are shown to be semantics modifiers. Experiments with these modifiers show the computational feasibility of this approach. Seven modifier projections are given which allow the efficient implementation of non-standard interpreters and non-standard compilers by program specialization or other powerful program transformation methods.