An Implementation of Session Types

A session type is an abstraction of a set of sequences of heterogeneous values sent and received over a communication channel. Session types can be used for specifying stream-based Internet protocols. Typically, session types are attached to communication-based program calculi, which renders them theoretical tools which are not readily usable in practice. To transfer session types into practice, we propose an embedding of a core calculus with session types into the functional programming language Haskell. The embedding preserves typing. A case study (a client for SMTP, the Simple Mail Transfer Protocol) demonstrates the feasibility of our approach.