Modular domain specific languages and tools

A domain specific language (DSL) allows one to develop software for a particular application domain quickly and effectively, yielding programs that are easy to understand, reason about, and maintain. On the other hand, there may be a significant overhead in creating the infrastructure needed to support a DSL. To solve this problem, a methodology is de-scribed for building domain specific embedded lan-guages (DSELs), in which a DSL is designed within an existing, higher-order and typed, programming lan-guage such as Haskell or ML. In addition, techniques are described for building modular interpreters and tools for DSELs. The resulting methodology facilitates reuse of syntax, semantics, implementation code, soft-ware tools, as well as look-and-feel