Re: Ranges and (non)static constraints

["Jeffrey R. Carter" <spam.not.jrcarter@acm.not.spam.org>]

Robert A Duff wrote:
> 
> OK.  I'm sure I will enjoy reading the RM for it someday.

As I will yours.

> But are you sure you want to define it by what it is NOT,
> rather than what it IS?  ;-)

I'll define it by what it is, and name it by what it isn't.

> String_Index seems reasonable for indexing strings.  Machine_Integer
> seems reasonable for a type that matches the machine's register size
> (but it should not be in Standard).  I think one wants a way to say
> (e.g.) that a type ranges from 1 up to at least a million, but it's fine
> to go beyond that, and please make it efficient (for example, perhaps
> round it up to 2**31-1).
> 
> Instead of Machine_Integer, perhaps we want a way to define a type that
> can count the number of Mumble objects, given that if we create more
> than some number of Mumble objects, or an array of them, we can be sure
> this count will not overflow.  That is, we would have run out of
> (virtual) memory before that count overflows.

That would have to be a dynamic type, as the actual upper bound could 
not generally be known at compile time.

-- 
Jeff Carter
"Ditto, you provincial putz?"
Blazing Saddles
86