The Importance of Mutability in Programming

In the real world, things are jumping around all the time. Should we model that in our code? Well, it turns out that it's much more liberating to have the constraint of keeping everything in a function. And even with effects, we see that amplified even more. Never jump out of the middle of a function with an exception or modify the,. You know, and then once you start doing it, you go, I can do more now because I don't have to think about that all the time."