Fully transitive const is not necessary

[Craig Black]

Walter/Andrei are under the impression that transitive const is necessary 
for multiprogramming, but they have not presented a detailed explanation 
about why it is necessary.  It sounds like a more detailed explanation of 
the merits of transitive const from Walter/Andrei would help here.

One idea that I had recently was that the const keyword could provide 
logical const (for developers) and the invariant keyword could provide 
transitive const (for the compiler).  I agree with you that for logical 
const, it is practical to have something like C++ mutable for class/struct 
fields.  I use C++ const, and it is practical to be able to subvert it.

-Craig