as in a chain of callbacks That's not what you said at first and there is no reason to assume that callbacks automatically mean a chain of callbacks. The inpu

as in a chain of callbacks That's not what you said at first and there is no reason to assume that callbacks automatically mean a chain of callbacks. The input-update-output loop is fine, but you cannot easily combine and nest such loops. So don't, where is this assumption that a technique is bad because it might ignore what makes it good and warp it into something terrible? For example, in a robot you may have a speed control inner loop, then a path following loop and on top of that a high-level behavior loop. Nesting one inside the others you end up with a hand-baked implementation of a coroutine. Then don't do that. You have a loop, do what you need inside of it. If you don't need to do something every time, skip it most of the time. This isn't rocket science. If a certain architecture doesn't work, don't do it like that. A car doesn't work well if you drive it backwards either.