Arrays, non-determinism, side-effects, and parallelism: A functional perspective

Abstract

Incremental, functional updates to arrays, executed in a non-deterministic manner, are shown to achieve the same effect (in both efficiency and functionality) as parallel assignment to imperative arrays. The strategy depends critically on the ability of a compiler to recognize not only that the incremental updates can be done destructively, but also that the updates may be done in any order. Special functional syntax is introduced that “captures” typical array-assignment patterns. The syntax falls somewhere in between the purely functional and (im)purely imperative, and makes the inferencing problem fairly easy. If nothing else, the work represents an interesting intellectual excercise in the relationship between non-determinism, side-effects, and parallelism.

Extended Abstract