Revive the enthusiasm for monoidal/reduction operations from Fortress

[masak]

The language Fortress is unfortunately not moving a lot these days. But Steele's 2009 talk about how to use associative operations/monoids/reduction to escape the sequential shackles of our past still shines like an important beacon across time.

Let's rescue the important lessons from that talk, and port them from Fortress to Alma. The main idea, after all, is just an API.

Better yet, we can extract and re-use the specific examples mentioned by Steele. These are the ones I remember:

• sum, product, max
• word count
• something about trapped rainwater

Maybe others? Certainly several others.