And the move to concurrent system which we’re not stepping back from ever. In concurrent system, mutable state is pain, you want to limit it. When most langag

And the move to concurrent system which we’re not stepping back from ever. In concurrent system, mutable state is pain, you want to limit it. When most langages make mutability ubiquitous it becomes very hard to understand that the issue is because 5 hours earlier a mutable array got unwittingly shared between two threads as it got sent as a message through a queue (thread-safe!) and now they’re stepping on each other’s toes when the stars align, and you end up with fishmen everywhere you go.