I appreciate the distinction, but I believe I disagree with allowing mutability on variables without explicit statements. In particular, I want to be able to e

I appreciate the distinction, but I believe I disagree with allowing mutability on variables without explicit statements. In particular, I want to be able to ensure that the only variation is the variation I explicitly state - for single threaded or for multithreaded code, I don't care. Having blobs of mutable state being passed around in a single threaded program is also a huge source of bugs. It is NOT a good idea. I don't have time today to tease out the implications of this proposal, but if it allows structs to be passed around and modified en-route in the same thread by default, just like C, then Rust loses a great deal of appeal. Sorry.