Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > comp.lang.python > #56374

Re: Tail recursion to while iteration in 2 easy steps

Path csiph.com!usenet.pasdenom.info!weretis.net!feeder4.news.weretis.net!rt.uk.eu.org!newsfeed.xs4all.nl!newsfeed2.news.xs4all.nl!xs4all!newsgate.cistron.nl!newsgate.news.xs4all.nl!post.news.xs4all.nl!not-for-mail
Return-Path <antoon.pardon@rece.vub.ac.be>
X-Original-To python-list@python.org
Delivered-To python-list@mail.python.org
X-Spam-Status OK 0.013
X-Spam-Evidence '*H*': 0.97; '*S*': 0.00; 'received:134': 0.05; 'level,': 0.07; 'assuming': 0.09; 'high-level': 0.09; 'subject:while': 0.09; 'runs': 0.10; 'def': 0.12; 'wrote': 0.14; 'formally': 0.16; 'janssen': 0.16; 'machine?': 0.16; 'rarely': 0.16; 'rebound': 0.16; 'subject:recursion': 0.16; 'wrote:': 0.18; 'normally': 0.19; 'written': 0.21; 'machine': 0.22; 'programming': 0.22; 'putting': 0.22; 'header:User-Agent:1': 0.23; 'mon,': 0.24; 'long,': 0.26; 'asking': 0.27; 'header:In-Reply-To:1': 0.27; "doesn't": 0.30; 'operations,': 0.30; "i'm": 0.30; 'code': 0.31; '-0700,': 0.31; "d'aprano": 0.31; 'description,': 0.31; 'operations.': 0.31; 'steven': 0.31; 'stuff': 0.32; 'problem': 0.35; 'something': 0.35; 'computing': 0.35; 'but': 0.35; 'functions.': 0.36; 'scheme': 0.36; 'doing': 0.36; 'useful': 0.36; 'possible': 0.36; 'list': 0.37; 'level': 0.37; 'expected': 0.38; 'sometimes': 0.38; 'others.': 0.38; 'somebody': 0.38; 'to:addr :python-list': 0.38; 'does': 0.39; 'sure': 0.39; 'to:addr:python.org': 0.39; 'how': 0.40; 'even': 0.60; 'tell': 0.60; 'gone': 0.61; 'challenge': 0.61; 'high': 0.63; 'such': 0.63; 'more': 0.64; 'here': 0.66; 'optimisation': 0.84; 'pardon': 0.84; '2013': 0.98
X-IronPort-Anti-Spam-Filtered true
X-IronPort-Anti-Spam-Result Ap4EACrNU1KGuA9G/2dsb2JhbABZwjqCeYE0gxkBAQWBCQsYCSUPAkYTCAKIArFQiRSOAoFGFoQNA5gBhiKLXoMmgWY
Date Tue, 08 Oct 2013 11:18:35 +0200
From Antoon Pardon <antoon.pardon@rece.vub.ac.be>
User-Agent Mozilla/5.0 (X11; Linux i686; rv:10.0.12) Gecko/20130116 Icedove/10.0.12
MIME-Version 1.0
To python-list@python.org
Subject Re: Tail recursion to while iteration in 2 easy steps
References <mailman.571.1380663065.18130.python-list@python.org> <87had0axxy.fsf@dpt-info.u-strasbg.fr> <CAMjeLr9KPf=Z4pJoQtU8LXiT686dABg-fpNoWYb9reEPRSsYjA@mail.gmail.com> <524C80B6.3010204@unistra.fr> <mailman.651.1380747919.18130.python-list@python.org> <87li292wnt.fsf@dpt-info.u-strasbg.fr> <mailman.732.1380925974.18130.python-list@python.org> <878uy52ea0.fsf@dpt-info.u-strasbg.fr> <5252F610.9040403@rece.vub.ac.be> <mailman.821.1381188514.18130.python-list@python.org> <525348d7$0$29984$c3e8da3$5496439d@news.astraweb.com>
In-Reply-To <525348d7$0$29984$c3e8da3$5496439d@news.astraweb.com>
Content-Type text/plain; charset=ISO-8859-1
Content-Transfer-Encoding 7bit
X-BeenThere python-list@python.org
X-Mailman-Version 2.1.15
Precedence list
List-Id General discussion list for the Python programming language <python-list.python.org>
List-Unsubscribe <https://mail.python.org/mailman/options/python-list>, <mailto:python-list-request@python.org?subject=unsubscribe>
List-Archive <http://mail.python.org/pipermail/python-list/>
List-Post <mailto:python-list@python.org>
List-Help <mailto:python-list-request@python.org?subject=help>
List-Subscribe <https://mail.python.org/mailman/listinfo/python-list>, <mailto:python-list-request@python.org?subject=subscribe>
Newsgroups comp.lang.python
Message-ID <mailman.840.1381223924.18130.python-list@python.org> (permalink)
Lines 42
NNTP-Posting-Host 2001:888:2000:d::a6
X-Trace 1381223924 news.xs4all.nl 15946 [2001:888:2000:d::a6]:59035
X-Complaints-To abuse@xs4all.nl
Xref csiph.com comp.lang.python:56374

Show key headers only | View raw

Op 08-10-13 01:50, Steven D'Aprano schreef:
> On Mon, 07 Oct 2013 15:47:26 -0700, Mark Janssen wrote:
> 
>> I challenge you to get
>> down to the machine code in scheme and formally describe how it's doing
>> both.
> 
> For which machine?
> 
> Or are you assuming that there's only one machine code that runs on all 
> computing devices?
> 
> 
> Frankly, asking somebody to *formally* describe a machine code 
> implementation strikes me as confused. Normally formal descriptions are 
> given in terms of abstract operations, often high level operations, 
> sometimes *very* high level, and rarely in terms of low-level "flip this 
> bit, copy this byte" machine code operations. I'm not sure how one would 
> be expected to generate a formal description of a machine code 
> implementation.
> 
> But even putting that aside, even if somebody wrote such a description, 
> it would be reductionism gone mad. What possible light on the problem 
> would be shined by a long, long list of machine code operations, even if 
> written using assembly mnemonics?
> 
> Far more useful would be a high-level description of Scheme's programming 
> model. If names can be rebound on the fly, how does Scheme even tell 
> whether something is a recursive call or not?
> 
> def foo(arg):
>     do stuff here
>     foo(arg-1)  # how does Scheme know that this is the same foo?

It doesn't and it doesn't need to. tail call optimisation is not
limited to recursive functions. All tail calls can be optimised,
recurisive call and others.

-- 
Antoon Pardon

Back to comp.lang.python | Previous | Next — Previous in thread | Next in thread | Find similar | Unroll thread

Thread

Tail recursion to while iteration in 2 easy steps Terry Reedy <tjreedy@udel.edu> - 2013-10-01 17:30 -0400
  Re: Tail recursion to while iteration in 2 easy steps rusi <rustompmody@gmail.com> - 2013-10-01 22:16 -0700
    Re: Tail recursion to while iteration in 2 easy steps Alain Ketterlin <alain@dpt-info.u-strasbg.fr> - 2013-10-02 10:23 +0200
      Re: Tail recursion to while iteration in 2 easy steps rusi <rustompmody@gmail.com> - 2013-10-02 06:29 -0700
    Re: Tail recursion to while iteration in 2 easy steps Ravi Sahni <ganeshsahni07@gmail.com> - 2013-10-03 22:57 +0530
      Re: Tail recursion to while iteration in 2 easy steps rusi <rustompmody@gmail.com> - 2013-10-04 03:52 -0700
  Re: Tail recursion to while iteration in 2 easy steps Alain Ketterlin <alain@dpt-info.u-strasbg.fr> - 2013-10-02 10:17 +0200
    Re: Tail recursion to while iteration in 2 easy steps Mark Janssen <dreamingforward@gmail.com> - 2013-10-02 11:59 -0700
    Re: Tail recursion to while iteration in 2 easy steps Mark Janssen <dreamingforward@gmail.com> - 2013-10-02 14:05 -0700
      Re: Tail recursion to while iteration in 2 easy steps Alain Ketterlin <alain@dpt-info.u-strasbg.fr> - 2013-10-04 11:49 +0200
        Re: Tail recursion to while iteration in 2 easy steps Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-10-04 10:51 +0000
        Re: Tail recursion to while iteration in 2 easy steps Terry Reedy <tjreedy@udel.edu> - 2013-10-04 18:32 -0400
          Re: Tail recursion to while iteration in 2 easy steps Alain Ketterlin <alain@dpt-info.u-strasbg.fr> - 2013-10-07 19:15 +0200
            Re: Tail recursion to while iteration in 2 easy steps Antoon Pardon <antoon.pardon@rece.vub.ac.be> - 2013-10-07 19:57 +0200
              Re: Tail recursion to while iteration in 2 easy steps Alain Ketterlin <alain@dpt-info.u-strasbg.fr> - 2013-10-08 10:56 +0200
                Re: Tail recursion to while iteration in 2 easy steps Jussi Piitulainen <jpiitula@ling.helsinki.fi> - 2013-10-08 12:49 +0300
            Re: Tail recursion to while iteration in 2 easy steps Terry Reedy <tjreedy@udel.edu> - 2013-10-07 16:42 -0400
            Re: Tail recursion to while iteration in 2 easy steps random832@fastmail.us - 2013-10-07 17:19 -0400
              Re: Tail recursion to while iteration in 2 easy steps Alain Ketterlin <alain@dpt-info.u-strasbg.fr> - 2013-10-08 10:41 +0200
            Re: Tail recursion to while iteration in 2 easy steps MRAB <python@mrabarnett.plus.com> - 2013-10-07 22:39 +0100
            Re: Tail recursion to while iteration in 2 easy steps Piet van Oostrum <piet@vanoostrum.org> - 2013-10-07 18:03 -0400
            Re: Tail recursion to while iteration in 2 easy steps Mark Janssen <dreamingforward@gmail.com> - 2013-10-07 15:47 -0700
              Re: Tail recursion to while iteration in 2 easy steps Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-10-07 23:50 +0000
                Re: Tail recursion to while iteration in 2 easy steps Mark Janssen <dreamingforward@gmail.com> - 2013-10-07 17:24 -0700
                Formal-ity and the Church-Turing thesis rusi <rustompmody@gmail.com> - 2013-10-07 20:17 -0700
                Re: Formal-ity and the Church-Turing thesis Ravi Sahni <ganeshsahni07@gmail.com> - 2013-10-08 10:46 +0530
                Re: Formal-ity and the Church-Turing thesis rusi <rustompmody@gmail.com> - 2013-10-07 22:44 -0700
                Re: Formal-ity and the Church-Turing thesis Mark Lawrence <breamoreboy@yahoo.co.uk> - 2013-10-08 07:43 +0100
                Re: Formal-ity and the Church-Turing thesis Ravi Sahni <ganeshsahni07@gmail.com> - 2013-10-08 18:31 +0530
                Re: Formal-ity and the Church-Turing thesis rusi <rustompmody@gmail.com> - 2013-10-08 06:33 -0700
                Re: Formal-ity and the Church-Turing thesis Steven D'Aprano <steve@pearwood.info> - 2013-10-08 07:50 +0000
                Re: Formal-ity and the Church-Turing thesis Ravi Sahni <ganeshsahni07@gmail.com> - 2013-10-08 18:16 +0530
                Re: Formal-ity and the Church-Turing thesis Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-10-08 13:11 +0000
                Re: Formal-ity and the Church-Turing thesis Robert Day <robertkday@gmail.com> - 2013-10-08 14:25 +0100
                Re: Formal-ity and the Church-Turing thesis Chris Angelico <rosuav@gmail.com> - 2013-10-09 08:36 +1100
                Re: Formal-ity and the Church-Turing thesis Mark Janssen <dreamingforward@gmail.com> - 2013-10-07 22:19 -0700
                Re: Formal-ity and the Church-Turing thesis rusi <rustompmody@gmail.com> - 2013-10-07 23:01 -0700
                Re: Formal-ity and the Church-Turing thesis Mark Janssen <dreamingforward@gmail.com> - 2013-10-08 10:39 -0700
                Re: Tail recursion to while iteration in 2 easy steps Mark Janssen <dreamingforward@gmail.com> - 2013-10-07 17:16 -0700
                Re: Tail recursion to while iteration in 2 easy steps Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-10-08 02:36 +0000
                Re: Tail recursion to while iteration in 2 easy steps Mark Janssen <dreamingforward@gmail.com> - 2013-10-07 20:27 -0700
                Re: Tail recursion to while iteration in 2 easy steps Steven D'Aprano <steve@pearwood.info> - 2013-10-08 09:22 +0000
                Re: Tail recursion to while iteration in 2 easy steps Charles Hixson <charleshixsn@earthlink.net> - 2013-10-09 15:45 -0700
                Re: Tail recursion to while iteration in 2 easy steps Piet van Oostrum <piet@vanoostrum.org> - 2013-10-07 22:46 -0400
                Re: Tail recursion to while iteration in 2 easy steps Jussi Piitulainen <jpiitula@ling.helsinki.fi> - 2013-10-08 10:25 +0300
                Re: Tail recursion to while iteration in 2 easy steps Antoon Pardon <antoon.pardon@rece.vub.ac.be> - 2013-10-08 11:18 +0200
              Re: Tail recursion to while iteration in 2 easy steps Piet van Oostrum <piet@vanoostrum.org> - 2013-10-07 22:45 -0400
                Re: Tail recursion to while iteration in 2 easy steps Mark Janssen <dreamingforward@gmail.com> - 2013-10-07 20:34 -0700
    Re: Tail recursion to while iteration in 2 easy steps Terry Reedy <tjreedy@udel.edu> - 2013-10-02 18:17 -0400
      Re: Tail recursion to while iteration in 2 easy steps Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-10-03 01:24 +0000
        Re: Tail recursion to while iteration in 2 easy steps Dave Angel <davea@davea.name> - 2013-10-03 01:39 +0000
        Re: Tail recursion to while iteration in 2 easy steps MRAB <python@mrabarnett.plus.com> - 2013-10-03 02:46 +0100
          Re: Tail recursion to while iteration in 2 easy steps Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-10-03 02:34 +0000
            Re: Tail recursion to while iteration in 2 easy steps Chris Angelico <rosuav@gmail.com> - 2013-10-03 14:14 +1000
            Re: Tail recursion to while iteration in 2 easy steps random832@fastmail.us - 2013-10-03 10:16 -0400
            Re: Tail recursion to while iteration in 2 easy steps Terry Reedy <tjreedy@udel.edu> - 2013-10-03 15:04 -0400
        Re: Tail recursion to while iteration in 2 easy steps Terry Reedy <tjreedy@udel.edu> - 2013-10-02 22:41 -0400
          Re: Tail recursion to while iteration in 2 easy steps Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-10-04 01:30 +0000
        Re: Tail recursion to while iteration in 2 easy steps Terry Reedy <tjreedy@udel.edu> - 2013-10-02 23:06 -0400
        Re: Tail recursion to while iteration in 2 easy steps random832@fastmail.us - 2013-10-03 10:14 -0400
        Literal syntax for frozenset, frozendict (was: Tail recursion to while iteration in 2 easy steps) Ben Finney <ben+python@benfinney.id.au> - 2013-10-04 10:18 +1000
        Re: Literal syntax for frozenset, frozendict Ethan Furman <ethan@stoneleaf.us> - 2013-10-03 18:31 -0700
    Re: Tail recursion to while iteration in 2 easy steps Duncan Booth <duncan.booth@invalid.invalid> - 2013-10-03 14:52 +0000
      Re: Tail recursion to while iteration in 2 easy steps Neil Cerutti <neilc@norwich.edu> - 2013-10-03 16:03 +0000
        Re: Tail recursion to while iteration in 2 easy steps Duncan Booth <duncan.booth@invalid.invalid> - 2013-10-04 10:16 +0000
          Re: Tail recursion to while iteration in 2 easy steps Ian Kelly <ian.g.kelly@gmail.com> - 2013-10-04 04:41 -0600
          Re: Tail recursion to while iteration in 2 easy steps Ian Kelly <ian.g.kelly@gmail.com> - 2013-10-04 04:46 -0600
            Re: Tail recursion to while iteration in 2 easy steps Duncan Booth <duncan.booth@invalid.invalid> - 2013-10-04 11:16 +0000
          Re: Tail recursion to while iteration in 2 easy steps Jussi Piitulainen <jpiitula@ling.helsinki.fi> - 2013-10-04 14:11 +0300
          Re: Tail recursion to while iteration in 2 easy steps Terry Reedy <tjreedy@udel.edu> - 2013-10-04 17:14 -0400
          Re: Tail recursion to while iteration in 2 easy steps Antoon Pardon <antoon.pardon@rece.vub.ac.be> - 2013-10-05 09:39 +0200
          Re: Tail recursion to while iteration in 2 easy steps random832@fastmail.us - 2013-10-07 17:27 -0400
            Re: Tail recursion to while iteration in 2 easy steps Jussi Piitulainen <jpiitula@ling.helsinki.fi> - 2013-10-08 10:11 +0300
          Re: Tail recursion to while iteration in 2 easy steps Antoon Pardon <antoon.pardon@rece.vub.ac.be> - 2013-10-08 11:43 +0200

csiph-web