Code reuse with language oriented programming

There is a gap between our ability to reuse high-level concepts in software design and our ability to reuse the code implementing them. Language Oriented Programming (LOP) is a software development paradigm that aims to close this gap, through extensive use of Domain Specific Languages (DSLs). With LOP, the high-level reusable concepts become reusable DSL constructs, and their translation into code level concepts is done in the DSL implementation. Particular products are implemented using DSL code, thus reusing only high-level concepts. In this paper we provide a comparison between two implementation approaches for LOP: (a),using external DSLs with a projectional language workbench (MPS); and (b),using internal DSLs with an LOP language (Cedalion). To demonstrate how reuse is achieved in each approach, we present a small case study, where LOP is used to build a Software Product Line (SPL) of calculator software.