The HDG-Machine: A Highly Distributed Graph-Reducer for a Transputer Network

Distributed implementations of programming languages with implicit parallelism hold out the prospect that the parallel programs are immediately scalable. This paper presents some of the results of our part of Esprit 415, in which we considered the implementation of lazy functional programming languages on distributed archi-tectures. A compiler and abstract machine were designed to achieve this goal. The abstract parallel machine was formally speciied, using Miranda 1. Each instruction of the abstract machine was then implemented as a macro in the Transputer Assem-bler. Although macro expansion of the code results in non-optimal code generation, use of the Miranda speciication makes it possible to validate the compiler before the Transputer code is generated. The hardware currently available consists of ve T800{25's, each board having 16M bytes of memory. Benchmark timings using this hardware are given. In spite of the straight forward code-generation, the resulting system compares favourably with more sophisticated sequential implementations, such as that of LML.