Algorithmic Skeletons in an Imperative Language for Distributed Programming

Algorithmic skeletons are functions representing common parallelization patterns and implemented in parallel. They can be used as the building blocks of parallel and distributed applications by integrating them into a sequential language. In this paper, we present a new approach to programming with skeletons. We integrate the skeletons into an imperative host language, which leads to important gains in eeciency. At the same time, we enhance the host language with some functional features, like higher-order functions and currying, as well as with a polymorphic type system, in order to allow high-level programming. After describing a series of skeletons which work with distributed arrays, we give two examples of parallel algorithms written as sequential programs, namely shortest paths in graphs and Gaussian elimination. Run-time measurements show that we approach the eecien-cy of message-passing C up to a factor between 1 and 2.5.