A Mixin-Based, Semantics-Based Approach to Reusing Domain-Specific Programming Languages

Domain-specific programming languages (DSLs) are emerging as an important paradigm for the engineering of large reliable software systems. Modular interpreters are an approach to building off-the-shelf software components that implement fragments of DSLs. We describe an approach to implementing modular interpreters in an object-oriented fashion, using the design pattern of extensible computations. The modular structuring and reuse of DSL implementations has potentially important lessons for object-oriented reuse, because of the highly recursive nature of any non-trivial programming language, and the close semantic relationship between inheritance and recursion. We give paradigmatic examples of the definition of extensible computations in the Java programming language, and consider what extensions would be required for typed object-oriented languages in order to support this approach in a statically type-safe manner.