Iteratee/Enumeratee is a way to process data -- file bytes, network datagrams or matrix elements -- incrementally, declaratively and with tight resource control. The approach has been inspired by fold, parser/printer combinators and circuit diagrams. There are several variants of the Iteratee-based I/O, available as independent libraries on Hackage or as part of bigger applications such as web servers. Here we give motivation, justification and explanation, pointing out earlier and experimental versions as well as related projects.

We present Cloud Haskell, a domain-specific language for developing programs for a distributed computing environment. Implemented as a shallow embedding in Haskell, it provides a messagepassing communication model, inspired by Erlang, without introducing incompatibility with Haskell’s established shared-memory
concurrency. A key contribution is a method for serializing function closures for transmission across the network. Cloud Haskell
has been implemented; we present example code and some preliminary performance measurements.