The "cool stuff" is in the commutative diagrams at the end of the article. They show that there are many different ways to train a distribution from data, some

The "cool stuff" is in the commutative diagrams at the end of the article. They show that there are many different ways to train a distribution from data, some of which will be more suited to different tasks. In most languages, we would have to program each of those paths separately. In Haskell, we get all of those paths "for free."