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Re: Possibly Pythonic Tail Call Optimization (TCO/TRE)

References (10 earlier) <87d1zunctp.fsf@elektro.pacujo.net> <mailman.503.1436878550.3674.python-list@python.org> <87k2u2eu67.fsf@elektro.pacujo.net> <CAPTjJmqtTRHpNZHByn1pKNSfbsG6X--s2d_G0FopKxDugqpjdA@mail.gmail.com> <55A51662.4090007@rece.vub.ac.be>
Date 2015-07-15 00:07 +1000
Subject Re: Possibly Pythonic Tail Call Optimization (TCO/TRE)
From Chris Angelico <rosuav@gmail.com>
Newsgroups comp.lang.python
Message-ID <mailman.507.1436882847.3674.python-list@python.org> (permalink)

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On Wed, Jul 15, 2015 at 12:02 AM, Antoon Pardon
<antoon.pardon@rece.vub.ac.be> wrote:
> On 07/14/2015 03:43 PM, Chris Angelico wrote:
>> On Tue, Jul 14, 2015 at 11:38 PM, Marko Rauhamaa <marko@pacujo.net> wrote:
>>> Chris Angelico <rosuav@gmail.com>:
>>>
>>>> On Tue, Jul 14, 2015 at 10:28 PM, Marko Rauhamaa <marko@pacujo.net> wrote:
>>>>> I would rather optimize by default and disable optimizations with
>>>>> --debug or equivalent.
>>>> That assumes that it's simply an optimization. This is a distinct
>>>> semantic change.
>>> No, tail call optimization doesn't change the behavior of the program,
>>> for the worse anyway.
>> It does, because you lose traceback records. That's pretty significant
>> when you come to try to debug something.
>
> I doubt it would be really significant. Not compared to writing it iteratively.
> When you write it iteratively, you don't get to keep a traceback record per time
> you go throught the loop. So the traceback records you loose in tale call elimination
> would be the traceback records you wouldn't have anyway in the iterative version.
>
> So how would this be significant?

You're proposing making _every_ instance of "return func(...)" into
this kind of thing. That's not always recursion, and it's certainly
not always clear what called what to get you there.

ChrisA

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Re: Possibly Pythonic Tail Call Optimization (TCO/TRE) Chris Angelico <rosuav@gmail.com> - 2015-07-14 00:05 +1000
  Re: Possibly Pythonic Tail Call Optimization (TCO/TRE) Steven D'Aprano <steve@pearwood.info> - 2015-07-14 13:20 +1000
    Re: Possibly Pythonic Tail Call Optimization (TCO/TRE) Antoon Pardon <antoon.pardon@rece.vub.ac.be> - 2015-07-14 09:26 +0200
    Re: Possibly Pythonic Tail Call Optimization (TCO/TRE) Ian Kelly <ian.g.kelly@gmail.com> - 2015-07-14 02:34 -0600
      Re: Possibly Pythonic Tail Call Optimization (TCO/TRE) Grant Edwards <invalid@invalid.invalid> - 2015-07-14 14:03 +0000
    Re: Possibly Pythonic Tail Call Optimization (TCO/TRE) Antoon Pardon <antoon.pardon@rece.vub.ac.be> - 2015-07-14 12:43 +0200
  Re: Possibly Pythonic Tail Call Optimization (TCO/TRE) Paul Rubin <no.email@nospam.invalid> - 2015-07-13 22:15 -0700
    Re: Possibly Pythonic Tail Call Optimization (TCO/TRE) Chris Angelico <rosuav@gmail.com> - 2015-07-14 15:25 +1000
      Re: Possibly Pythonic Tail Call Optimization (TCO/TRE) Paul Rubin <no.email@nospam.invalid> - 2015-07-13 22:41 -0700
        Re: Possibly Pythonic Tail Call Optimization (TCO/TRE) Chris Angelico <rosuav@gmail.com> - 2015-07-14 21:43 +1000
          Re: Possibly Pythonic Tail Call Optimization (TCO/TRE) Marko Rauhamaa <marko@pacujo.net> - 2015-07-14 15:28 +0300
            Re: Possibly Pythonic Tail Call Optimization (TCO/TRE) Chris Angelico <rosuav@gmail.com> - 2015-07-14 22:55 +1000
              Re: Possibly Pythonic Tail Call Optimization (TCO/TRE) Marko Rauhamaa <marko@pacujo.net> - 2015-07-14 16:38 +0300
                Re: Possibly Pythonic Tail Call Optimization (TCO/TRE) Chris Angelico <rosuav@gmail.com> - 2015-07-14 23:43 +1000
                Re: Possibly Pythonic Tail Call Optimization (TCO/TRE) Marko Rauhamaa <marko@pacujo.net> - 2015-07-14 20:29 +0300
                Re: Possibly Pythonic Tail Call Optimization (TCO/TRE) Steven D'Aprano <steve@pearwood.info> - 2015-07-15 03:48 +1000
                Re: Possibly Pythonic Tail Call Optimization (TCO/TRE) Antoon Pardon <antoon.pardon@rece.vub.ac.be> - 2015-07-15 10:28 +0200
                Re: Possibly Pythonic Tail Call Optimization (TCO/TRE) Antoon Pardon <antoon.pardon@rece.vub.ac.be> - 2015-07-14 16:02 +0200
                Re: Possibly Pythonic Tail Call Optimization (TCO/TRE) Chris Angelico <rosuav@gmail.com> - 2015-07-15 00:07 +1000
                Re: Possibly Pythonic Tail Call Optimization (TCO/TRE) Marko Rauhamaa <marko@pacujo.net> - 2015-07-14 20:31 +0300
                Re: Possibly Pythonic Tail Call Optimization (TCO/TRE) Terry Reedy <tjreedy@udel.edu> - 2015-07-14 20:41 -0400
                Re: Possibly Pythonic Tail Call Optimization (TCO/TRE) Antoon Pardon <antoon.pardon@rece.vub.ac.be> - 2015-07-15 11:10 +0200
                Re: Possibly Pythonic Tail Call Optimization (TCO/TRE) Gregory Ewing <greg.ewing@canterbury.ac.nz> - 2015-07-16 10:43 +1200
                Re: Possibly Pythonic Tail Call Optimization (TCO/TRE) Antoon Pardon <antoon.pardon@rece.vub.ac.be> - 2015-07-16 09:31 +0200
                Re: Possibly Pythonic Tail Call Optimization (TCO/TRE) Gregory Ewing <greg.ewing@canterbury.ac.nz> - 2015-07-17 10:41 +1200
                Re: Possibly Pythonic Tail Call Optimization (TCO/TRE) Chris Angelico <rosuav@gmail.com> - 2015-07-16 21:45 +1000
                Re: Possibly Pythonic Tail Call Optimization (TCO/TRE) Antoon Pardon <antoon.pardon@rece.vub.ac.be> - 2015-07-16 15:56 +0200
                Re: Possibly Pythonic Tail Call Optimization (TCO/TRE) Chris Angelico <rosuav@gmail.com> - 2015-07-17 00:00 +1000
                Re: Possibly Pythonic Tail Call Optimization (TCO/TRE) Antoon Pardon <antoon.pardon@rece.vub.ac.be> - 2015-07-16 16:32 +0200
                Re: Possibly Pythonic Tail Call Optimization (TCO/TRE) Chris Angelico <rosuav@gmail.com> - 2015-07-17 02:43 +1000
                Re: Possibly Pythonic Tail Call Optimization (TCO/TRE) Joonas Liik <liik.joonas@gmail.com> - 2015-07-16 19:50 +0300
                Re: Possibly Pythonic Tail Call Optimization (TCO/TRE) Chris Angelico <rosuav@gmail.com> - 2015-07-17 03:03 +1000
                Re: Possibly Pythonic Tail Call Optimization (TCO/TRE) Ethan Furman <ethan@stoneleaf.us> - 2015-07-16 10:04 -0700
                Re: Possibly Pythonic Tail Call Optimization (TCO/TRE) Joonas Liik <liik.joonas@gmail.com> - 2015-07-16 20:34 +0300
                Re: Possibly Pythonic Tail Call Optimization (TCO/TRE) Steven D'Aprano <steve@pearwood.info> - 2015-07-17 04:58 +1000
                Re: Possibly Pythonic Tail Call Optimization (TCO/TRE) Joonas Liik <liik.joonas@gmail.com> - 2015-07-16 22:14 +0300
                Re: Possibly Pythonic Tail Call Optimization (TCO/TRE) Gregory Ewing <greg.ewing@canterbury.ac.nz> - 2015-07-17 11:41 +1200
                Re: Possibly Pythonic Tail Call Optimization (TCO/TRE) Ethan Furman <ethan@stoneleaf.us> - 2015-07-16 12:52 -0700
                Re: Possibly Pythonic Tail Call Optimization (TCO/TRE) Chris Angelico <rosuav@gmail.com> - 2015-07-17 03:49 +1000
                Re: Possibly Pythonic Tail Call Optimization (TCO/TRE) Joonas Liik <liik.joonas@gmail.com> - 2015-07-16 21:23 +0300
                Re: Possibly Pythonic Tail Call Optimization (TCO/TRE) Chris Angelico <rosuav@gmail.com> - 2015-07-17 04:29 +1000
                Re: Possibly Pythonic Tail Call Optimization (TCO/TRE) Terry Reedy <tjreedy@udel.edu> - 2015-07-16 16:19 -0400
                Re: Possibly Pythonic Tail Call Optimization (TCO/TRE) Antoon Pardon <antoon.pardon@rece.vub.ac.be> - 2015-07-17 12:48 +0200
                Re: Possibly Pythonic Tail Call Optimization (TCO/TRE) Gregory Ewing <greg.ewing@canterbury.ac.nz> - 2015-07-19 10:57 +1200
                Re: Possibly Pythonic Tail Call Optimization (TCO/TRE) Chris Angelico <rosuav@gmail.com> - 2015-07-17 21:05 +1000
                Re: Possibly Pythonic Tail Call Optimization (TCO/TRE) Antoon Pardon <antoon.pardon@rece.vub.ac.be> - 2015-07-17 13:43 +0200
                Re: Possibly Pythonic Tail Call Optimization (TCO/TRE) Chris Angelico <rosuav@gmail.com> - 2015-07-17 21:49 +1000
                Re: Possibly Pythonic Tail Call Optimization (TCO/TRE) Antoon Pardon <antoon.pardon@rece.vub.ac.be> - 2015-07-17 14:54 +0200
                Re: Possibly Pythonic Tail Call Optimization (TCO/TRE) Chris Angelico <rosuav@gmail.com> - 2015-07-17 23:12 +1000
                Re: Possibly Pythonic Tail Call Optimization (TCO/TRE) Terry Reedy <tjreedy@udel.edu> - 2015-07-17 16:27 -0400
          Re: Possibly Pythonic Tail Call Optimization (TCO/TRE) Gregory Ewing <greg.ewing@canterbury.ac.nz> - 2015-07-15 21:13 +1200
            Re: Possibly Pythonic Tail Call Optimization (TCO/TRE) Marko Rauhamaa <marko@pacujo.net> - 2015-07-15 12:55 +0300
            Re: Possibly Pythonic Tail Call Optimization (TCO/TRE) Mark Lawrence <breamoreboy@yahoo.co.uk> - 2015-07-15 12:22 +0100
              Re: Possibly Pythonic Tail Call Optimization (TCO/TRE) Gregory Ewing <greg.ewing@canterbury.ac.nz> - 2015-07-16 10:34 +1200
                Re: Possibly Pythonic Tail Call Optimization (TCO/TRE) Mark Lawrence <breamoreboy@yahoo.co.uk> - 2015-07-16 00:34 +0100
            Re: Possibly Pythonic Tail Call Optimization (TCO/TRE) MRAB <python@mrabarnett.plus.com> - 2015-07-15 13:00 +0100
            Re: Possibly Pythonic Tail Call Optimization (TCO/TRE) Chris Angelico <rosuav@gmail.com> - 2015-07-15 22:13 +1000
              Re: Possibly Pythonic Tail Call Optimization (TCO/TRE) Gregory Ewing <greg.ewing@canterbury.ac.nz> - 2015-07-16 10:34 +1200
            Re: Possibly Pythonic Tail Call Optimization (TCO/TRE) Chris Angelico <rosuav@gmail.com> - 2015-07-15 22:22 +1000
      Re: Possibly Pythonic Tail Call Optimization (TCO/TRE) Marko Rauhamaa <marko@pacujo.net> - 2015-07-14 08:41 +0300
        Re: Possibly Pythonic Tail Call Optimization (TCO/TRE) Chris Angelico <rosuav@gmail.com> - 2015-07-14 21:33 +1000
          Re: Possibly Pythonic Tail Call Optimization (TCO/TRE) Marko Rauhamaa <marko@pacujo.net> - 2015-07-14 15:08 +0300
    Re: Possibly Pythonic Tail Call Optimization (TCO/TRE) Chris Angelico <rosuav@gmail.com> - 2015-07-14 15:31 +1000
    Re: Possibly Pythonic Tail Call Optimization (TCO/TRE) Ian Kelly <ian.g.kelly@gmail.com> - 2015-07-13 23:46 -0600
      Re: Possibly Pythonic Tail Call Optimization (TCO/TRE) Marko Rauhamaa <marko@pacujo.net> - 2015-07-14 08:57 +0300
        Re: Possibly Pythonic Tail Call Optimization (TCO/TRE) Gregory Ewing <greg.ewing@canterbury.ac.nz> - 2015-07-14 18:29 +1200
          Re: Possibly Pythonic Tail Call Optimization (TCO/TRE) Marko Rauhamaa <marko@pacujo.net> - 2015-07-14 10:05 +0300
            Re: Possibly Pythonic Tail Call Optimization (TCO/TRE) Gregory Ewing <greg.ewing@canterbury.ac.nz> - 2015-07-15 17:52 +1200
              Re: Possibly Pythonic Tail Call Optimization (TCO/TRE) Marko Rauhamaa <marko@pacujo.net> - 2015-07-15 09:44 +0300
                Re: Possibly Pythonic Tail Call Optimization (TCO/TRE) Ned Batchelder <ned@nedbatchelder.com> - 2015-07-15 03:45 -0700
                Re: Possibly Pythonic Tail Call Optimization (TCO/TRE) Marko Rauhamaa <marko@pacujo.net> - 2015-07-15 13:55 +0300
                Re: Possibly Pythonic Tail Call Optimization (TCO/TRE) Antoon Pardon <antoon.pardon@rece.vub.ac.be> - 2015-07-15 13:04 +0200
                Re: Possibly Pythonic Tail Call Optimization (TCO/TRE) Ned Batchelder <ned@nedbatchelder.com> - 2015-07-15 04:12 -0700
                Re: Possibly Pythonic Tail Call Optimization (TCO/TRE) Marko Rauhamaa <marko@pacujo.net> - 2015-07-15 14:24 +0300
                Re: Possibly Pythonic Tail Call Optimization (TCO/TRE) Rustom Mody <rustompmody@gmail.com> - 2015-07-16 21:28 -0700
          Re: Possibly Pythonic Tail Call Optimization (TCO/TRE) Mark Lawrence <breamoreboy@yahoo.co.uk> - 2015-07-14 08:47 +0100
        Re: Possibly Pythonic Tail Call Optimization (TCO/TRE) Ian Kelly <ian.g.kelly@gmail.com> - 2015-07-14 02:13 -0600
          Re: Possibly Pythonic Tail Call Optimization (TCO/TRE) Marko Rauhamaa <marko@pacujo.net> - 2015-07-14 11:33 +0300
            Re: Possibly Pythonic Tail Call Optimization (TCO/TRE) Ian Kelly <ian.g.kelly@gmail.com> - 2015-07-14 07:15 -0600
              Re: Possibly Pythonic Tail Call Optimization (TCO/TRE) Marko Rauhamaa <marko@pacujo.net> - 2015-07-14 20:27 +0300
                Re: Possibly Pythonic Tail Call Optimization (TCO/TRE) Ian Kelly <ian.g.kelly@gmail.com> - 2015-07-15 08:28 -0600
                Re: Possibly Pythonic Tail Call Optimization (TCO/TRE) Marko Rauhamaa <marko@pacujo.net> - 2015-07-15 17:55 +0300
            Re: Possibly Pythonic Tail Call Optimization (TCO/TRE) Steven D'Aprano <steve@pearwood.info> - 2015-07-15 03:34 +1000
              Re: Possibly Pythonic Tail Call Optimization (TCO/TRE) Marko Rauhamaa <marko@pacujo.net> - 2015-07-14 20:43 +0300
                Re: Possibly Pythonic Tail Call Optimization (TCO/TRE) Chris Angelico <rosuav@gmail.com> - 2015-07-15 03:52 +1000
                Re: Possibly Pythonic Tail Call Optimization (TCO/TRE) Steven D'Aprano <steve@pearwood.info> - 2015-07-15 04:06 +1000
                Re: Possibly Pythonic Tail Call Optimization (TCO/TRE) Marko Rauhamaa <marko@pacujo.net> - 2015-07-14 21:37 +0300
                Re: Possibly Pythonic Tail Call Optimization (TCO/TRE) Chris Angelico <rosuav@gmail.com> - 2015-07-15 04:55 +1000
                Re: Possibly Pythonic Tail Call Optimization (TCO/TRE) Marko Rauhamaa <marko@pacujo.net> - 2015-07-14 22:12 +0300
                Re: Possibly Pythonic Tail Call Optimization (TCO/TRE) Terry Reedy <tjreedy@udel.edu> - 2015-07-14 21:36 -0400
                Re: Possibly Pythonic Tail Call Optimization (TCO/TRE) Terry Reedy <tjreedy@udel.edu> - 2015-07-14 21:01 -0400
                Re: Possibly Pythonic Tail Call Optimization (TCO/TRE) Chris Angelico <rosuav@gmail.com> - 2015-07-15 13:05 +1000
              Re: Possibly Pythonic Tail Call Optimization (TCO/TRE) Paul Rubin <no.email@nospam.invalid> - 2015-07-14 10:54 -0700
    Re: Possibly Pythonic Tail Call Optimization (TCO/TRE) Terry Reedy <tjreedy@udel.edu> - 2015-07-14 20:23 -0400

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