Internal DSLs are a special kind of DSLs that use an existing programming language as their host. To build them successfully, knowledge regarding how to modify the host language is essential. In this chapter, the author contributes six DSL design principles and 21 DSL design patterns. DSL Design principles provide guidelines that identify specific design goals to shape the syntax and semantic of a DSL. DSL design patterns express proven knowledge about recurring DSL design challenges, their solution, and their connection to each other – forming a rich vocabulary that developers can use to explain a DSL design and share their knowledge. The chapter presents design patterns grouped into foundation patterns (which provide the skeleton of the DSL consisting of objects and methods), notation patterns (which address syntactic variations of host language expressions), and abstraction patterns (which provide the domain-specific abstractions as extensions or even modifications of the host language semantics).
Agile Engineering of Internal Domain-Specific Languages with Dynamic Programming Languages