655 Pscheme: Extending Continuations to Express Control and Synchronization in a Parallel LISP C. Yao, B. Goldberg, March, 1994 In this paper, we describe Pscheme, a parallel dialect of Scheme. The primary construct for specifying parallelism, synchronization, and communication is a natural extension of first-class continuations which we call a port. We describe the behavior of ports, along with the other parallel constructs of Pscheme. Because the user has precise control over the parallel computation, the Pscheme constructs can be used to build higher-level parallel programming abstractions, such as futures, semaphores, and Ada-style rendezvous. We provide the Pscheme code for these abstractions and discuss the current implementation of Pscheme on a shared-memory multiprocessor.