Communicating Haskell Processes: Composable Explicit Concurrency using Monads

Abstract

Writing concurrent programs in languages that lack explicit support for concurrency can often be awkward and difficult. Haskell's monads provide a way to explicitly specify sequence and effects in a functional language, and monadic combi- nators allow composition of monadic actions, for example via parallelism and choice - two core aspects of Communicating Sequential Processes (CSP). We show how the use of these combinators, and being able to express processes as first-class types (monadic actions) allow for easy and elegant programming of process-oriented concurrency in a new CSP library for Haskell: Communicating Haskell Processes.