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Groups > comp.lang.python > #55466
| From | Duncan Booth <duncan.booth@invalid.invalid> |
|---|---|
| Newsgroups | comp.lang.python |
| Subject | Re: Tail recursion to while iteration in 2 easy steps |
| Date | 2013-10-04 10:16 +0000 |
| Message-ID | <XnsA24F724671D8duncanbooth@127.0.0.1> (permalink) |
| References | <mailman.571.1380663065.18130.python-list@python.org> <87had0axxy.fsf@dpt-info.u-strasbg.fr> <XnsA24EA12FAD49Cduncanbooth@127.0.0.1> <bb5ireFbpf3U1@mid.individual.net> |
Neil Cerutti <neilc@norwich.edu> wrote:
> On 2013-10-03, Duncan Booth <duncan.booth@invalid.invalid> wrote:
>> It isn't hard to imagine adding a TAIL_CALL opcode to the
>> interpreter that checks whether the function to be called is
>> the same as the current function and if it is just updates the
>> arguments and jumps to the start of the code block.
>
> Tail call optimization doesn't involve verification that the
> function is calling itself; you just have to verfify that the
> call is in tail position.
You misunderstood me. As usually implemented tail call recursion doesn't
require verifying that the function is calling itself, but in Python the
function could be rebound so a check would be a necessary protection
against this unlikely situation. Consider this Python:
@some_decorator
def fact(n, acc=1):
if n <= 1:
return acc
return fact(n-1, n*acc)
Is that tail recursion or not?
You cannot tell whether or not that is tail recursion unless you know the
definition of 'some_decorator' and even then the answer may vary from run
to run.
--
Duncan Booth http://kupuguy.blogspot.com
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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
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