Re: Ranges and (non)static constraints

["Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de>]

On Fri, 17 Nov 2006 18:58:00 -0500, Robert A Duff wrote:

> If I say:
> 
>     type T is range 1..1_000_000_000_000;
> 
> some implementations fail at compile time, and some do not.  That's bad,
> too.  I ought to be allowed to say, portably:
> 
>     type T is range 1..10**100;

Yes, that's my point. I would also add:

   type T is range <>;  -- A true bignum, like Unbounded_String

>>... And there'd be type Unbounded_Integer, providing
>> use of the unbounded-integer library used by the compiler.
> 
> Well, I'll quibble with your names, here.  When God created the
> integers, He didn't say they stop at 2**31-1 or 2**64 or whatever!
> The term "integer" (or the abbreviation "int") ought to mean the true
> unbounded integers.  Names like Unbounded_Integer and _universal_integer
> are an abomination.  ;-)

Yes, but there is a naming problem of different things:

1. An unconstrained set of integer numbers = mathematical Integer, bignum.
No bounds, whatsoever, similar to Unbounded_String.

2. A finite subset of, which bounds are unknown until run-time, similar to
String.

3. A finite subset with statically known bounds, similar to String (1..80).

Ideally, both 3 and 2 should be defined in terms of 1.

BTW, what about

   type M is mod <>;

This looks as a bit harder nut. Considering:

   X : M := 23; -- Hmm, which the modulo here? (:-))

-- 
Regards,
Dmitry A. Kazakov
http://www.dmitry-kazakov.de