Comment by yxhuvud
5 years ago
OTOH, at some point what is good from a cognitive viewpoint depends on what idioms you use. So it can be helpful to actively chose which idioms you use and make certain to not use those that tend to blow up performance wise.
Given the current code example, I don't even thing idioms come into it. Here a hash map data structure was called for regardless of whatever idioms come into other parts of the design. This is just fundamental and has nothing to do with functional programming, OOP, etc.