[exabrial]

They’re fine if they are self contained, which is your point, and which is the author’s point (and generally everyone else). He didn’t go into detail of the why, but that is east is usually meant.

A good clean programming have it is to wrap all of your stream()/lambdas chains in a static method that describes what they do. This make sure they don’t have access to the local scope and can mutate data.