There's one thing that bothers me about Swift, and I feel like I must not be getting it. For the most part it looks like a very well-designed language, and the

There's one thing that bothers me about Swift, and I feel like I must not be getting it. For the most part it looks like a very well-designed language, and the choices they made are extremely pragmatic. But the way collection mutability is determined seems positively insane. You can't have a mutable reference to an immutable array, or vice-versa. I don't get the reasoning behind that.