A new array operation

Abstract

A new monolithic array operation has been proposed. The operation is similar to earlier proposals, except that it uses the fold operation to combine multiple values with the same index. The new operation conveniently handles certain important kinds of computation, such as histogram, and provides parallelism in a convenient way.

This method solves the important problem of calculating histograms in a fashion suitable for parallel computation. I-structures, devised by Arvind and his colleagues, sacrifice referential transparency in order to increase the opportunities for parallelism, but do not provide a good solution to the histogram problem. I am grateful to Arvind for pointing out this defect of I-structures, which in turn inspired this paper.

Although the method presented here is useful for an important class of problems, it is not the best solution for all problems involving arrays. Further experience is needed to assess its advantages and shortcomings.