Domain-Specific Languages with Scala.

Domain-Specific Languages (DSLs) are often classified into external and internal DSLs. An external DSL is a stand-alone language with its own parser. An internal DSL is an extension of an existing programming language, the host language, offering the user of the DSL domain-specific constructs as well as the constructs of the host language, thus providing a richer language than the DSL itself. In this paper we report on experiences implementing external as well as internal formal modeling DSLs with the Scala programming language, known in particular for its support for defining DSLs. The modeling languages include monitoring logics, a testing language, and a general purpose SysML inspired modeling language. We present a systematic overview of advantages and disadvantages of each option.