HAL: A High-Level Actor Language and Its Distributed Implementation

We describe Hal, a high-level, actor-based language which has served as a test-bed for experimenting with powerful linguistic constructs for parallel and distributed programming. Hal is an architecture independent, concurrent object-oriented language which supports inheritance, synchronization constraints, continuation capture, synchronous and asynchronous message passing, and re ection. The Hal compiler has been used to execute actor programs on a number of shared and distributed memory machines. Hal allows powerful abstractions to be dened and reused. Furthermore, Hal supports the use of synchronization constraints at a ne-grained level and the use of software pipelining. In this paper, we describe the design of Hal, using speci c examples to illustrate its features. We then discuss some of the implementation issues in the run-time system.