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,FREEMAIL_FROM
	autolearn=unavailable autolearn_force=no version=3.4.4
X-Received: by 10.99.96.209 with SMTP id u200mr1318277pgb.28.1499838131494;
        Tue, 11 Jul 2017 22:42:11 -0700 (PDT)
X-Received: by 10.36.83.73 with SMTP id n70mr35743itb.0.1499838131453; Tue, 11
 Jul 2017 22:42:11 -0700 (PDT)
Path: 
 eternal-september.org!reader01.eternal-september.org!reader02.eternal-september.org!news.eternal-september.org!news.eternal-september.org!feeder.eternal-september.org!news.glorb.com!188no104412itx.0!news-out.google.com!196ni26itl.0!nntp.google.com!v202no107738itb.0!postnews.google.com!glegroupsg2000goo.googlegroups.com!not-for-mail
Newsgroups: comp.lang.ada
Date: Tue, 11 Jul 2017 22:42:11 -0700 (PDT)
In-Reply-To: <ok26bp$lt4$1@dont-email.me>
Complaints-To: groups-abuse@google.com
Injection-Info: glegroupsg2000goo.googlegroups.com;
 posting-host=62.235.158.22;
 posting-account=nuF4hQoAAADjc2KKS1rOkzxWWEmaDrvx
NNTP-Posting-Host: 62.235.158.22
References: <oju353$b75$1@gioia.aioe.org> <ok001a$rhm$1@gioia.aioe.org>
 <ok26bp$lt4$1@dont-email.me>
User-Agent: G2/1.0
MIME-Version: 1.0
Message-ID: <0260f40d-0737-4d92-a2e3-bcada4cbcb20@googlegroups.com>
Subject: Re: Generators/coroutines in future Ada?
From: darkestkhan <darkestkhan@gmail.com>
Injection-Date: Wed, 12 Jul 2017 05:42:11 +0000
Content-Type: text/plain; charset="UTF-8"
Content-Transfer-Encoding: quoted-printable
Xref: news.eternal-september.org comp.lang.ada:47369
Date: 2017-07-11T22:42:11-07:00
List-Id: <comp.lang.ada>

On Tuesday, July 11, 2017 at 9:42:59 AM UTC, J-P. Rosen wrote:
> Le 10/07/2017 =C3=A0 15:38, Victor Porton a =C3=A9crit :
> > But AFAIK Ada does not support closures.
> >=20
> > Are closures really needed to implement generators?
> >=20
> > It is nearly impossible to add closures to Ada, right?
>=20
> Taking the example from Wikipedia:
>=20
> function startAt(x)
>    function incrementBy(y)
>        return x + y
>    return incrementBy
>=20
> variable closure1 =3D startAt(1)
> variable closure2 =3D startAt(5)
>=20
> This could be written as:
> generic
>    Start_Value : Integer
> function Increment_By (X : integer) return Integer;
>=20
> function Closure1 is new Increment_By (1);
> function Closure2 is new Increment_By (5);
>=20
> ----
> I can hear you saying that "generics are a poor man's workaround for the
> lack of closure", to which I respond that closures are a limited
> workaround for the lack of the more general concept of generic...
>=20
> TBH, I don't think there is any value in the kind of discussion that
> starts with "Language X is lacking feature A from language Y".
>=20
> Express a problem in language Y, let people provide their solution in
> language X, and then we can discuss the merits of each solution, given
> some quality criteria. Note that sometimes, criteria can be at odds;
> f.e., people nowadays value ease of writing and flexibility very much,
> but these are quite opposed to safety, readability, and long term
> maintenance which form the basic requirements of Ada.
>=20
> --=20
> J-P. Rosen
> Adalog
> 2 rue du Docteur Lombard, 92441 Issy-les-Moulineaux CEDEX
> Tel: +33 1 45 29 21 52, Fax: +33 1 45 29 25 00
> http://www.adalog.fr

Other ways in which this can be done (beside generic package with state):
- task
- protected object
- additional argument of [tagged] limited type

Likely some other ways are possible. I just don't see what is the point of =
special construct for generators when we got at least 4 ways to do it.