> One way to do that would be to collect all actions done in each frame (instead of mutating) and then apply them all to create a new frame in a single step (a

> One way to do that would be to collect all actions done in each frame (instead of mutating) and then apply them all to create a new frame in a single step (a "reduce") This is actually a reliable way to construct most programs; it can aid significantly with reasoning, debugging, and performance. I try to build software this way whenever I can.