That's a bit of a misconception about FP though. Immutability is just the default, and you can opt into local mutability when you need to. Clojure transients ar

That's a bit of a misconception about FP though. Immutability is just the default, and you can opt into local mutability when you need to. Clojure transients are a good example of this. So, in a case of a game, I would create local mutable sections for the tight loop. It's also worth noting that modern hardware hasn't been using imperative CPU models for a long time, and it provides an emulation layer that languages like C target https://queue.acm.org/detail.cfm?id=3212479 https://queue.acm.org/detail.cfm?id=3212479