Systems Need Domain-Specific Languages

Building construction, like most domains, has developed a rich language with a vocabulary, idioms, and patterns^[21] that convey essential information clearly and concisely. In software, there has been renewed interest recently in creating Domain-Specific Languages (DSLs),^[22] which are separate, small scripting languages or APIs in standard languages that permit code to be written so that it reads like a structured form of prose that a domain expert might write.

^[21] The work of [Alexander] has been particularly influential on the software community.

^[22] See, for example, [DSL]. [JMock] is a good example of a Java API that creates a DSL.

A good DSL minimizes the “communication gap” between a domain concept and the code that implements it, just as agile practices optimize the communications within a team and with the project’s stakeholders. If you are implementing domain logic in the same language that a domain expert uses, there is less risk that you will incorrectly translate the domain into the implementation.