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Groups > comp.lang.python > #94075

Re: A new module for performing tail-call elimination

Date 2015-07-19 01:19 +0100
From MRAB <python@mrabarnett.plus.com>
Subject Re: A new module for performing tail-call elimination
References (2 earlier) <mo6iq5$vqk$1@ger.gmane.org> <55A76116.7070708@rece.vub.ac.be> <mailman.606.1437075284.3674.python-list@python.org> <87lhefanui.fsf@elektro.pacujo.net> <d102t1F8rq4U1@mid.individual.net>
Newsgroups comp.lang.python
Message-ID <mailman.689.1437265194.3674.python-list@python.org> (permalink)

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On 2015-07-18 23:39, Gregory Ewing wrote:
> Marko Rauhamaa wrote:
>> At any rate, it demonstrates how the idiom has its place in Python.
>
> Perhaps it does, but I think I'd still prefer it to be
> explicit.
>
> The call in Marko's example is not actually a tail call
> as written. To make it a tail call, a return would need
> to be added:
>
>   >       return child.setvalue(keyseq, value, offset + 1)
>
> To someone reading the code, it's not obvious why the
> return is there. It looks redundant, and is likely to
> get removed by someone who thinks it's a mistake.
>
> Using a dedicated keyword would make it clear that tail
> call behaviour is being relied upon, and avoid looking
> like a spurious return.
>
Of the current reserved words, the choice is between 'continue' and
'pass'.

How clear is:

     continue child.setvalue(keyseq, value, offset + 1)

?

I think the problem is that it reads like it's something to do with
co-routines.

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Thread

A new module for performing tail-call elimination "Th. Baruchel" <baruchel@no.spam.gmx.dot.com> - 2015-07-13 15:44 +0000
  Re: A new module for performing tail-call elimination Antoon Pardon <antoon.pardon@rece.vub.ac.be> - 2015-07-15 11:29 +0200
    Re: A new module for performing tail-call elimination Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2015-07-16 18:07 +1000
      Re: A new module for performing tail-call elimination Robin Becker <robin@reportlab.com> - 2015-07-16 10:13 +0100
      Re: A new module for performing tail-call elimination Robin Becker <robin@reportlab.com> - 2015-07-16 10:28 +0100
        Re: A new module for performing tail-call elimination Marko Rauhamaa <marko@pacujo.net> - 2015-07-16 12:56 +0300
      Re: A new module for performing tail-call elimination Antoon Pardon <antoon.pardon@rece.vub.ac.be> - 2015-07-16 12:41 +0200
        Re: A new module for performing tail-call elimination Steven D'Aprano <steve@pearwood.info> - 2015-07-17 04:58 +1000
          Re: A new module for performing tail-call elimination Antoon Pardon <antoon.pardon@rece.vub.ac.be> - 2015-07-17 11:00 +0200
      Re: A new module for performing tail-call elimination Chris Angelico <rosuav@gmail.com> - 2015-07-16 21:11 +1000
      Re: A new module for performing tail-call elimination Jeremy Sanders <jeremy@jeremysanders.net> - 2015-07-16 13:29 +0200
      Re: A new module for performing tail-call elimination Antoon Pardon <antoon.pardon@rece.vub.ac.be> - 2015-07-16 15:35 +0200
      Re: A new module for performing tail-call elimination Chris Angelico <rosuav@gmail.com> - 2015-07-16 23:47 +1000
        Re: A new module for performing tail-call elimination Paul Rubin <no.email@nospam.invalid> - 2015-07-17 20:06 -0700
      Re: A new module for performing tail-call elimination Antoon Pardon <antoon.pardon@rece.vub.ac.be> - 2015-07-16 16:21 +0200
      Re: A new module for performing tail-call elimination Chris Angelico <rosuav@gmail.com> - 2015-07-17 00:27 +1000
      Re: A new module for performing tail-call elimination Antoon Pardon <antoon.pardon@rece.vub.ac.be> - 2015-07-16 17:14 +0200
      Re: A new module for performing tail-call elimination Ian Kelly <ian.g.kelly@gmail.com> - 2015-07-16 10:17 -0600
      Re: A new module for performing tail-call elimination Ethan Furman <ethan@stoneleaf.us> - 2015-07-16 10:54 -0700
      Re: A new module for performing tail-call elimination Ethan Furman <ethan@stoneleaf.us> - 2015-07-16 11:02 -0700
      Re: A new module for performing tail-call elimination Terry Reedy <tjreedy@udel.edu> - 2015-07-16 15:45 -0400
      Re: A new module for performing tail-call elimination Ethan Furman <ethan@stoneleaf.us> - 2015-07-16 12:58 -0700
      Re: A new module for performing tail-call elimination Robin Becker <robin@reportlab.com> - 2015-07-17 09:57 +0100
    Re: A new module for performing tail-call elimination Alain Ketterlin <alain@universite-de-strasbourg.fr.invalid> - 2015-07-16 13:23 +0200
  Re: A new module for performing tail-call elimination Terry Reedy <tjreedy@udel.edu> - 2015-07-15 17:19 -0400
  Re: A new module for performing tail-call elimination Antoon Pardon <antoon.pardon@rece.vub.ac.be> - 2015-07-16 09:45 +0200
  Re: A new module for performing tail-call elimination Terry Reedy <tjreedy@udel.edu> - 2015-07-16 15:34 -0400
    Re: A new module for performing tail-call elimination Marko Rauhamaa <marko@pacujo.net> - 2015-07-16 22:45 +0300
      Re: A new module for performing tail-call elimination Terry Reedy <tjreedy@udel.edu> - 2015-07-17 15:47 -0400
        Re: A new module for performing tail-call elimination Marko Rauhamaa <marko@pacujo.net> - 2015-07-17 23:55 +0300
          Re: A new module for performing tail-call elimination Terry Reedy <tjreedy@udel.edu> - 2015-07-17 20:40 -0400
            Re: A new module for performing tail-call elimination Gregory Ewing <greg.ewing@canterbury.ac.nz> - 2015-07-19 10:39 +1200
          Re: A new module for performing tail-call elimination Chris Angelico <rosuav@gmail.com> - 2015-07-18 10:47 +1000
          Re: A new module for performing tail-call elimination Gregory Ewing <greg.ewing@canterbury.ac.nz> - 2015-07-19 10:39 +1200
      Re: A new module for performing tail-call elimination Gregory Ewing <greg.ewing@canterbury.ac.nz> - 2015-07-19 10:39 +1200
        Re: A new module for performing tail-call elimination Mark Lawrence <breamoreboy@yahoo.co.uk> - 2015-07-19 01:09 +0100
        Re: A new module for performing tail-call elimination MRAB <python@mrabarnett.plus.com> - 2015-07-19 01:19 +0100
        Re: A new module for performing tail-call elimination Marko Rauhamaa <marko@pacujo.net> - 2015-07-19 09:29 +0300
  Re: A new module for performing tail-call elimination Antoon Pardon <antoon.pardon@rece.vub.ac.be> - 2015-07-17 10:06 +0200

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