From mboxrd@z Thu Jan  1 00:00:00 1970
X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) on polar.synack.me
X-Spam-Level: 
X-Spam-Status: No, score=-1.9 required=5.0 tests=BAYES_00
	autolearn=unavailable autolearn_force=no version=3.4.4
Path: 
 eternal-september.org!reader01.eternal-september.org!reader02.eternal-september.org!news.eternal-september.org!news.eternal-september.org!news.eternal-september.org!feeder.eternal-september.org!news.glorb.com!feed.news.qwest.net!mpls-nntp-01.inet.qwest.net!132.250.1.121.MISMATCH!ra.nrl.navy.mil!bloom-beacon.mit.edu!bloom-beacon.mit.edu!newsswitch.lcs.mit.edu!nntp.TheWorld.com!.POSTED!not-for-mail
From: Robert A Duff <bobduff@shell01.TheWorld.com>
Newsgroups: comp.lang.ada
Subject: Re: Your wish list for Ada 202X
Date: Thu, 03 Apr 2014 18:56:34 -0400
Organization: The World Public Access UNIX, Brookline, MA
Message-ID: <wcctxaa81jx.fsf@shell01.TheWorld.com>
References: <7f1c01c5-3563-4b94-9831-152dbbf2ecdc@googlegroups.com>
 <2d62368c-9f64-49f3-98a8-5121d0c0fa23@googlegroups.com>
 <wccy4zmphp6.fsf@shell01.TheWorld.com> <lhkfo9$rt4$1@speranza.aioe.org>
NNTP-Posting-Host: shell01.theworld.com
Mime-Version: 1.0
Content-Type: text/plain; charset=us-ascii
X-Trace: pcls7.std.com 1396565800 8827 192.74.137.71 (3 Apr 2014 22:56:40 GMT)
X-Complaints-To: abuse@TheWorld.com
NNTP-Posting-Date: Thu, 3 Apr 2014 22:56:40 +0000 (UTC)
User-Agent: Gnus/5.1008 (Gnus v5.10.8) Emacs/21.3 (irix)
Cancel-Lock: sha1:I9b7ddbAz+UOizDoIwvWmBYREfY=
Xref: news.eternal-september.org comp.lang.ada:19101
Date: 2014-04-03T18:56:34-04:00
List-Id: <comp.lang.ada>

Qun-Ying <zhu.qunying@gmail.com> writes:

> Robert A Duff wrote:
>> But I agree with you that Ada ought to require[*] 64-bit integers
>> (and more, as Jeff Carter said).  On the other hand, I have
>> no use for Standard.Long_Long_Integer -- I just want to be
>> able to say things like "range 1..2**123".
>> - Bob
>>
> What prevents a compiler to implement that in the current standard?

Nothing prevents it.  It would cost money, though.

Also, users might be surprised that:

    type Biggest_Integer is range System.Min_Int .. System.Max_Int;

is extremely inefficient.

And as I said, standards don't require anybody to do (or not do)
anything.  Standards compliance is optional.  So even if the Ada
RM forbade that, a compiler could allow it anyway (probably in
a special mode, so it could still honestly claim conformance).

But the fact that a compiler can implement very large integers
isn't much use to people who care about portability to all
conforming implementations.

> Couldn't the compiler use internal representation (like using the gmp
> lib) for such big range?

It could.

In fact, recent versions of GNAT support arbitrary-range integers
for intermediate results.  See Appendix D, "Overflow Check Handling
in GNAT" in the GNAT User's Guide.

- Bob