preparing for const, final, and invariant

[Walter Bright]

Bill Baxter wrote:
> That makes sense to me too.  If you don't say anything it's 'scope const 
> final'.  But if you do specify something then it's only that.

Right. There are too many qualifies to do otherwise.

> I'm not 
> wild about the aesthetics of !const for parameters, and even less wild 
> about the possibility that !const could become common idiom for 
> modifiable parameters.  If it's a common way to pass a parameter, then 
> there should be a way to express the attribute positively (like 
> "mutable" or "variable" or "inout") in terms of what it does do, rather 
> than what it doesn't.

Uh, I think you put a finger on just where I was getting a bad feeling 
about !const. It's generally confusing to use negatives as attributes, 
i.e., having state variables named:
	"notFull"
is a bad idea.

I'm at the moment thinking we should just bite the bullet and introduce 
'mutable' as a keyword.