Servant provides a type-level
domain-specific language (DSL) to describe
World Wide Web application programming interfaces (
Web APIs); various interpretations of such descriptions are possible: as a
server, which dispatches requests to handlers; as documentation and schema specifications for the API; and as client libraries in various languages. The type-level approach by Servant solves the
expression problem by allowing the extensibility along the dimensions of both data and behavior. ==Use==