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

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Date 2015-07-16 22:14 +0300
Subject Re: Possibly Pythonic Tail Call Optimization (TCO/TRE)
From Joonas Liik <liik.joonas@gmail.com>
Newsgroups comp.lang.python
Message-ID <mailman.604.1437074064.3674.python-list@python.org> (permalink)

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On 16 July 2015 at 21:58, Steven D'Aprano <steve@pearwood.info> wrote:
> On Fri, 17 Jul 2015 03:34 am, Joonas Liik wrote:
>
>> Now i admit that it is possible to have infinite recursion but it is
>> also possiblew to have infinite loops. and we don't kill your code
>> after 1000 iterations of a while loop so why should we treat recursion
>> any differently?
>
> Because a while loop which repeats to many times is annoying but harmless,
> but a function that recurses too many times will blow up the stack and
> cause a seg fault, possibly executing arbitrary memory as code. You want
> malware and viruses to take over your system? That's how you get malware
> and viruses to take over your system.

That's just a buggy implementation, there are ways to extend the stack
that nears its capacity, safely.

>
>> Having a user defined maximum stack limit might be a good idea, eg if
>> my stack takes up 100MB its prolly broke, but it should be my duty as
>> a programmer to specify such a limit, not have it inflicted upon me
>> (worse, in a manner that cannot be changed!).
>
> You mean sys.getrecursionlimit() and sys.setrecursionlimit()?
>
... and that buggy implementation means that when you
sys.setrecursionlimit() you will overflow the stack and crash because
the recursion limit is an aritificial safeguard and the underlying c
buffer is not adjusted accordingly or at least so it would seem.

https://docs.python.org/2/library/sys.html#sys.setrecursionlimit
so as per the docs the programmer has no real control over how much
stack his program can have. all you can say is "let me ignore the
safeguard a little longer, i hope i wont crash the program" that is
not the same as "can i please have a stack depth of 20000..

You are giving the programmer a choice between "run out of stack and
crash" and "mutilate interpreter internals and crash or zero out the
hard drive" this is not a real choice..

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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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