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:
and gives me confidence that my algorithm is a monoid.