I don't see how functional programming would ever solve the problem of chronology. If the collision engine needs to know the new position in that frame then it

I don't see how functional programming would ever solve the problem of chronology. If the collision engine needs to know the new position in that frame then it needs to run that code first. You can't just run code whenever and expect functional programming to fix it. Nor will assigning different areas of the state to specific functions fix that either. I think immutable data solves a lot of headaches and using Redux and Immutable together in our current stack has shown me some of the benefits of immutability and a more functional programming style. However, much of this article was about immutability not being a silver bullet for things that, IMO, were never going to be solved by immutability. It's like saying it would be solved by writing everything in Haskell, there are some "complexities" that can't be hidden, e.g. order of events. Maybe I missed something.