Executable Specification Language for Parallel Symbolic Computation

摘要

Two goals, simplicity of program designing, and efficiency of its computation, always remain topical in programming, and more than anything this is true about parallel programming systems. The former goal is usually achieved for declarative programming languages, the latter - by embedding of coordination level operators. One of the earliest such extensions, future annotation, isa proposed in . Their use allows to start a function computation before the moment when computation of its annotated arguments will be completed. Another advance to increase program parallelization was using of nondeterministic operators in pseudo-functional languages. One more resource widely used in logic programming to program parallelization is speculative computation of alternative branches. In this paper we propose SL specification language that combines all of these features: 1) future annotating; 2) speculative annotating to point out conditional operators whose alternatives can be started to compute before the condition value will be determined; 3) sets as data structures and a nondeterministic choice operator with erratic choice semantics. Such nondeterminism allows to choose elements from a set even if there are other set's elements that are in progress. Another pecularity of our approach is SL program transformations during compile time stage illustrated below by an example.