Guy Steele's word split example using Groovy and GPars

The Fortress programming language has some very powerful features. Guy Steele's slides here (slides 52 onwards) illustrate some of its features including how to split a sentence into words in parallel.

Here we look at some ways to use Groovy and GPars to solve that problem.

First we can write an imperative sequential version:

And test it as follows:

Now, we can ask ourselves a question. Is this solution in its current form easy to turn into a parallel solution? The answer is NO. Each step in our loop relies on the result from the previous step. If I split the sentence into two pieces, and I am processing the start of the second piece, I don't know whether a character or space finished the previous piece. It means that my algorithm when operating on the data isn't associative. Or stating it another way, the order in which I process information is important in the current algorithm.

This produces the output:

200 tests

and gives me confidence that my algorithm is a monoid.