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=ham
	autolearn_force=no version=3.4.4
X-Google-Thread: 103376,5948949183cbd10c,start
X-Google-NewGroupId: yes
X-Google-Attributes: gida07f3367d7,domainid0,public,usenet
X-Google-Language: ENGLISH,ASCII-7-bit
Received: by 10.180.84.234 with SMTP id c10mr42545wiz.4.1351655922910;
        Tue, 30 Oct 2012 20:58:42 -0700 (PDT)
Path: 
 ha8ni90417wib.1!nntp.google.com!fu-berlin.de!uni-berlin.de!individual.net!not-for-mail
From: Bill Findlay <yaldnif.w@blueyonder.co.uk>
Newsgroups: comp.lang.ada
Subject: Dynamic_Predicate  with a generic
Date: Wed, 31 Oct 2012 03:58:40 +0000
Message-ID: <CCB65270.20246%yaldnif.w@blueyonder.co.uk>
Mime-Version: 1.0
X-Trace: individual.net
 ns1ZoHcvowYgN3UH9rp+BgL0Ocje+3v+dhMnSCDr8W4xk5GKyfrjPpokITPppglHZ7
Cancel-Lock: sha1:uZLDH7LUI99RoWD25ID2chp9U9Y=
User-Agent: Microsoft-Entourage/12.33.0.120411
Thread-Topic: Dynamic_Predicate  with a generic
Thread-Index: Ac23HALyBasPSW4jpUOp6XgQ6vMRhQ==
Content-Type: text/plain;
	charset="US-ASCII"
Content-Transfer-Encoding: 7bit
Date: 2012-10-31T03:58:40+00:00
List-Id: <comp.lang.ada>

The following code compiles:
> 
>    type integral          is new Integer;
>    type unsigned_integral is mod 2**32;
> 
>    subtype nat_integral is integral range 0 .. integral'Last;
>    subtype pos_integral is integral range 1 .. integral'Last;
> 
>    -- returns True iff nr is a prime number
>    function is_prime (nr : integral) return Boolean;
> 
>    subtype prime_number is integral
>       with Dynamic_Predicate => is_prime(prime_number);
> 

But if the types integral and unsigned_integral are given by generic type
parameters, thus:

> generic
>    type integral          is range <>;
>    type unsigned_integral is mod <>;
> package prime_numbers is
> 
>     pragma Elaborate_Body;
> 
>    subtype nat_integral is integral range 0 .. integral'Last;
>    subtype pos_integral is integral range 1 .. integral'Last;
> 
>    -- returns True iff nr is a prime number
>    function is_prime (nr : integral) return Boolean;
> 
>    subtype prime_number is integral
>       with Dynamic_Predicate => is_prime(prime_number);

I get the error message:

> 
> ==============Error messages for source file: prime_numbers.ads
>     20.       with Dynamic_Predicate => is_prime(prime_number);
>                                                  |
>>>> invalid use of subtype mark in expression or call

What am I missing?

-- 
Bill Findlay
with blueyonder.co.uk;
use  surname & forename;