[runT1ME]

>Beyond the magic of map/flatmap/etc, the things that allow you to achieve terseness

I think if you assume 'terseness' is the goal of constructs such as map/flatMap you're missing the forest for the trees. Yes terseness can be a good thing, it sacrifices familiarity for the ability to understand more going on in a quicker amount of time. This can definitely reduce cognitive overheard for someone familiar with the constructs being used.

This however, is a secondary (but pleasant) side effect of the main goal which is (non leaky) abstraction. By using familiar abstractions it allows readers to reason about code in a powerful way, allowing for more reuse and composition.