Concurrent Scheme

This paper describes an evolution of the Scheme language to support parallelism with tight coupling of control and data. Mechanisms are presented to address the difficult and related problems of mutual exclusion and data sharing which arise in concurrent language systems. The mechanisms are tailored to preserve Scheme semantics as much as possible while allowing for efficient implementation. Prototype implementations of the resulting language are described which have been completed. A third implementation is underway for the Mayfly, a distributed memory, twisted-torus communication topology, parallel processor, under development at the Hewlett-Packard Research Laboratories. The language model is particularly well suited for the Mayfly processor, as will be shown.