> This is a systems language, which means you should have the choice to do efficient things, if you know what you're doing. You shouldn't be told "you can't do

> This is a systems language, which means you should have the choice to do efficient things, if you know what you're doing. You shouldn't be told "you can't do that because you might get it wrong. I don't have the time to watch the video right now, so maybe I'm reading this out of context, but how does compiler-enforced immutability change this? I'm not asking for everything to be immutable (not even in Haskell is that true) -- I'm just asking for the ability to mark an object as immutable and have the compiler make sure that it isn't modified. I'd prefer that non-local objects be immutable by default, but I'm willing to live with mutable by default. Really, immutable state gives you the efficiency of pointers coupled with the nice semantics of copy-by-value. It's the best of both worlds -- not having it is denying the programmer "the choice to do efficient things".