[M3devel] INTEGER

[Tony Hosking]

Let me see.

The green book definition says the base type of a subrange of INTEGER literals is INTEGER.
You say that the base type of a subrange of LONGINT literals is LONGINT.
But you say that LONGINT is not a defined type.  So, what is the type of a LONGINT literal?
...

[I think I misunderstood you previously. I had interpreted that you meant LONGINT subranges to have base type INTEGER.]

On 22 Apr 2010, at 08:38, hendrik at topoi.pooq.com wrote:

> On Thu, Apr 22, 2010 at 11:57:16AM -0400, Tony Hosking wrote:
>> But this is bizarre.  What type does an element of a subrange of 
>> LONGINT have if not LONGINT?
> 
> It has LONGINT as a type.
> 
>> If the subrange has a base type of INTEGER then we need a mapping 
>> between the elements of the subrange and the base INTEGER values.
> 
> Yes.  And INTEGER is different from the notion mathematicians have of 
> integers in that there is a limit on the size of integers.  It's a 
> machine or implementation-dependent limit, and it's imposed for 
> efficiency reasons, but it's a specific limit just the same.
> This limit is precisely what we're up against.
> 
>> But then, values of the LONGINT subrange don't have the same 
>> representation as their INTEGER counterpart.
> 
> Of course not.  If they did have the same representation, there would be 
> in-range for INTEGERs, and there would be no need to have LONGINT at 
> all.
> 
> LONGINT is there precisely for the integers that *don't* fit in INTEGER.
> 
>> 
>> All very odd.
> 
> But dictated by the intended use -- that of having integral ranges
> whose bounds are dictated by the problem, not the hardware.
> 
> -- hendrik