dsl

A domain-specific language (DSL) is a programming or specification language dedicated to a particular problem domain, as opposed to a general-purpose language. DSLs can be external, with their own syntax and tooling, or internal (embedded) within a host language.

Examples of external DSLs include SQL for data querying, CSS for styling, and regular expressions for text matching. Internal DSLs are implemented as libraries or language features in a host language, providing DSL-like syntax while reusing the host’s tooling and ecosystem.

Design goals for DSLs include expressing domain concepts more directly, increasing productivity, and enabling domain experts to specify rules and constraints without general programming. Tradeoffs include limited flexibility outside the domain, the need for specialized tooling, potential maintenance burden, and the risk of creating siloed ecosystems with bespoke tooling.

DSLs differ from general-purpose languages by scope and abstraction level. They are often designed to be easier to learn for domain experts and to reduce boilerplate within the domain, though they require careful balancing of expressiveness and simplicity. DSLs can be built as external languages with parsers and compilers or as embedded DSLs in languages such as Ruby, Kotlin, C#, or Python.

Common domains for DSLs include databases, user interfaces, hardware design, build and deployment automation, and configuration management. Adoption depends on domain complexity, the volume of repetitive tasks, and the availability of existing tooling and expertise.