Comment by kilgnad
1 year ago
Lambda calculus machines can't exist in reality though. Only the von Neumann machine can be actualized.
Thus from a practical perspective the foundations of actual computing must be built on mutable state.
You are wrong about the generations idea. It's a side effect. Functions themselves cannot actually do anything with a generation number. It's completely useless other then for letting you know how many times a value has changed.
A generation number also doesn't negate the need for mutexes. The system is still operating on shared state, a generation number doesn't change this.
You are not getting the point of either my comment or the original article. You are thinking from an engineering point of view, where if you look through all the layers of abstraction you see mutexes and shared mutable memory. That's not my point; my point is about building up those abstractions so they are sufficiently hidden. Functional programmers routinely operate on a higher level of abstraction, and they have shorter, more maintainable code. In such code, it would be a code smell if you continue to use mutexes, because that should've been an implementation detail. It should've been clear from the outset that the kind of complexity the article is talking about is cognitive complexity.
I am getting it. I am simply saying that you can't completely hide those details. They leak through.