> If you mix FP and OO you'll often end up with terrible FP which simply reproduces the "old" approach: lots of mutable stuff everywhere. What I'm suggesting i

> If you mix FP and OO you'll often end up with terrible FP which simply reproduces the "old" approach: lots of mutable stuff everywhere. What I'm suggesting is that mutable state isn't inherently bad. It's entirely possible that we will someday enter a new age of mainstream, pure FP where we look back at mutable state and cringe. But that's pure speculation. Our current world is full of successful applications written in languages built on mutable state. So I'm not saying that mutable state is inherently better than the alternatives. Just that the case against it--and for the alternatives--has to be pretty darn compelling to outweigh the tremendous real-world success of languages like Ruby, Python, JavaScript, and so on.