Well it doesn't get you there because shared-mutable-safe doesn't exist, at least I doubt it can without major tradeoffs. You either err on the side of complete safety with a system that is borderline unusable for anything practical, or you let people do whatever they want and let them deal with their problems once they actually have them.
> either way that's a huge blow to 'shared' if you are only allowed one writer
Yeah for full N thread reading and editing you'd need N vars per var which is annoying, but that kind of every-thread-is-main setup is something that is exceedingly rare. There's almost always a few fixed main ones and lots running specific tasks that don't really need to know about all the other ones.
> either way that's a huge blow to 'shared' if you are only allowed one writer
Yeah for full N thread reading and editing you'd need N vars per var which is annoying, but that kind of every-thread-is-main setup is something that is exceedingly rare. There's almost always a few fixed main ones and lots running specific tasks that don't really need to know about all the other ones.