Eden - The Paradise of Functional Concurrent Programming

The functional concurrent language Eden 1] is an extension of the lazy functional language Haskell 4] by constructs for the explicit speciication of dynamic process systems. It employs stream-based communication and is tailored for distributed memory systems. Eden supports and facilitates the task of parallel and concurrent programming. Eden incorporates special concepts for the eecient treatment of general reac-tive systems, i.e. systems which maintain some interaction with the environment and which may be time-dependent. The dynamic creation of reply channels sim-pliies the generation of complex communication topologies and increases the exibility of the language. Predeened nondeterministic processes MERGE and SPLIT are used to model many-to-one and one-to-many communication in process systems. Eden incorporates a two level structure: the level of user-deened processes and the level of process systems. User-deened processes can be seen as determin-istic mappings from input channels to output channels. Nondeterminism is only handled at the system level which consists of all (predeened and user-deened) processes interacting via communication on channels. 1 Eden in a nutshell Haskell forms the computation language of Eden. This is extended by a coordination model that introduces processes in a functional style, embodying constructs which allow for the deenition and creation of processes, communication and synchronization, and the speciication of interconnections between processes. Eden distinguishes between process abstractions, which specify process behaviour in a purely functional way, and process instantiations in which process abstractions are supplied with input values in order to create new processes. A process abstraction deenes a general parameterized process scheme. It speciies a process which maps (streams of) input values in 1 , : : : , in m to (streams of) output values out