Concurrent Haskell

Some applications are most easily expressed in a programming language that supports concurrency, notably interactive and distributed systems. We propose extensions to the purely functional language Haskell that allow it to express explicitly concurrent applications; we call the resulting language Concurrent Haskell. The resulting system appears to be both expressive and efficient and we give a number of examples of useful abstractions that can be built from our primitives. We have developed a freely available implementation of Concurrent Haskell and are now using it as a substrate for a graphical user interface toolkit.