Fully transitive const is not necessary

[Jason House]

Walter Bright wrote:

> Bill Baxter wrote:
>> If the ultimate goal is support for multiprogramming, then shouldn't the
>> detailed design work should start *there*, with how to do great
>> multiprogramming?  Rather than with const.
>> 
>> Not saying that you guys have done this, but I know from my own
>> experience doing research that it's easy to get hung up trying to solve
>> a tough but solvable problem that seems relevant for getting from A to
>> B, only to realize in the end that it was not as relevant as I thought.
> 
> I think it is fairly obvious that transitive invariant (and const) is
> key to multiprogramming. The transitive closure of the state of
> everything reachable through an object is part of the state of that
> object, and all the troubles with multiprogramming stem from the state
> of an object changing asynchronously.

And how do global variables fit into that?  Technically, they're always
reachable and never inherit const.