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!feeder.eternal-september.org!aioe.org!.POSTED!not-for-mail
From: "Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de>
Newsgroups: comp.lang.ada
Subject: Re: use of 'Base to compensate for the lack of information
Date: Wed, 27 Dec 2017 14:28:17 +0100
Organization: Aioe.org NNTP Server
Message-ID: <p2075j$m0$1@gioia.aioe.org>
References: <dc81f170-1442-48d8-af5d-a929cfabfdcb@googlegroups.com>
NNTP-Posting-Host: TliDXSPe+gBSGCqP3SEJ2Q.user.gioia.aioe.org
Mime-Version: 1.0
Content-Type: text/plain; charset=utf-8; format=flowed
Content-Transfer-Encoding: 7bit
X-Complaints-To: abuse@aioe.org
User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:52.0) Gecko/20100101
 Thunderbird/52.5.2
X-Notice: Filtered by postfilter v. 0.8.2
Content-Language: en-US
Xref: reader02.eternal-september.org comp.lang.ada:49652
Date: 2017-12-27T14:28:17+01:00
List-Id: <comp.lang.ada>

On 2017-12-27 13:29, Mehdi Saada wrote:

> It seems good and practical, but at one time, I need the coefficient 
> to be multiplied by the coefficients' array index, which is a
> Natural.

Does not make sense, but ...

> So, I wrote
>      with function "*" (E1: in ELEMENT; E2: in NATURAL'Base) return ELEMENT is <>;
> 
> But since X'Base meant the unconstrained subtype of X, any type
> defined as "type T is range ..." won't fit in.

Since it is not Integer, yes.

> Yet I don't want any
> assumption on the nature of ELEMENT. It could be defined as Integer,
> Natural, modular types, or be rational made of modular types in case of
> FINITE FIELDS.

Array index of a rational type? That makes any array except empty and 
singleton countably infinite, well, well.

> How do I do while keeping that generic design ?

    type Index is range <>;
    with function "*" (Left : Element; Right : Index)
       return Element is <>;

  [ with function "*" (Left, Right : Element) return Element is <>; ]

If you want it be any copyable type, then

    type Bandersnatch is private;
    with function "*" (Left : Element; Right : Bandersnatch)
       return Element is <>;

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