I find it interesting how in a large codebase or project there is a temptation to mutate an object here, decorate some intermediate object there, and before you

I find it interesting how in a large codebase or project there is a temptation to mutate an object here, decorate some intermediate object there, and before you know it you have an ugly state machine hiding in your code. As you know the number of possible states grows very fast and when people don't know this is happening things soon get out of control. Having things immutable by default helps somewhat, but it's still easy to add various decorators.