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,b4a4dceda94869d2
X-Google-NewGroupId: yes
X-Google-Attributes: gida07f3367d7,domainid0,public,usenet
X-Google-Language: ENGLISH,ASCII-7-bit
Received: by 10.68.35.131 with SMTP id h3mr98516pbj.1.1320811951370;
        Tue, 08 Nov 2011 20:12:31 -0800 (PST)
Path: 
 h5ni15110pba.0!nntp.google.com!news2.google.com!news4.google.com!feeder2.cambriumusenet.nl!feed.tweaknews.nl!192.87.166.28.MISMATCH!tudelft.nl!txtfeed1.tudelft.nl!feed.xsnews.nl!border-3.ams.xsnews.nl!eternal-september.org!feeder.eternal-september.org!.POSTED!not-for-mail
From: "R. Tyler Croy" <tyler@linux.com>
Newsgroups: comp.lang.ada
Subject: Re: Iterators in Ada2012
Date: Wed, 9 Nov 2011 04:12:29 +0000 (UTC)
Organization: A noiseless patient Spider
Message-ID: <j9cujd$g3k$1@dont-email.me>
References: 
 <66dbca36-0248-458a-aff4-1176d6ce098b@m10g2000vbc.googlegroups.com>
	<4eb92ae0$0$6581$9b4e6d93@newsspool3.arcor-online.net>
Mime-Version: 1.0
Injection-Date: Wed, 9 Nov 2011 04:12:29 +0000 (UTC)
Injection-Info: mx04.eternal-september.org;
 posting-host="RGN/TepX2HLLmCAUtZUpgw";
	logging-data="16500"; mail-complaints-to="abuse@eternal-september.org";
	posting-account="U2FsdGVkX18ACZrs2drDF36DHM68ui2a"
User-Agent: Pan/0.135 (Tomorrow I'll Wake Up and Scald Myself with Tea; GIT
	30dc37b master)
Cancel-Lock: sha1:KoKkMXY3FnRQTo9caJGowxdIND0=
Xref: news2.google.com comp.lang.ada:14362
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit
Date: 2011-11-09T04:12:29+00:00
List-Id: <comp.lang.ada>

On Tue, 08 Nov 2011 14:13:03 +0100, Georg Bauhaus wrote:

> On 08.11.11 11:05, comp.lang.php wrote:
>> I have an instantiation of the package Ada.Containers.Ordered_Maps
>> (Integer, Float). Is there a neat way of iterating over the values
>> similar to the construction:
>> for x of a_Set loop ... end loop.
> 
> Fear of nesting a procedure? :-)
> 
> I had thought that the new syntax of AI 139 would be for all containers.
> 
> Strangely, the fashion seems to be moving elsewhere:
> list comprehensions, Map + Reduce (US Patent #7,650,331), Scala,
> ... all functional, hence little sympathy for for-loops. Sequence
> comprehensions are now recommended when writing Python, so I had thought
> there is all the more to say in favor of a simple automatic
> 
>   Container.Iterate (Process => Meaningful_Name'Access).

The reasons things like list comprehensions and generator expressions are 
recommended in Python is because they're faster in the CPython 
implementation of the language since they get to native C "faster" (with 
less interpretation and bytecode).

Additionally, generator expressiones: `(x for x in iterable)` are lazily 
evaluated so you don't have to actually have your working set in memory 
all at once.

An Ada "built-in" equivalent of a generator expression I actually don't 
know of, I suppose you could hide that behind your Container.Iterate 
procedure?



Cheers

-- 
- R. Tyler Croy
--------------------------------------
    Code: http://github.com/rtyler