Qlisp: Parallel Processing in Lisp

One of the major problems in writing programs to take advantage of parallel processing has been the lack of good multiprocessing languages|one which is both powerful and understandable to programmers. In this paper we describe multiprocessing extensions to Common Lisp designed to be suitable for studying styles of parallel programming at the medium-grain level in a shared-memory architecture. The resulting language is called Qlisp. A problem with parallel programming is the degree to which the programmer must explicitly address synchronization problems. Two new approaches to this problem look promising: the rst is the concept of heavyweight futures, and the second is a new type of function called a partially, multiply invoked function.