Re: Suggestion: make sequence and map interfaces more similar

From	Manolo Martínez <manolo@austrohungaro.com>
Newsgroups	comp.lang.python
Subject	Re: Suggestion: make sequence and map interfaces more similar
Date	2016-03-30 15:13 +0200
Message-ID	<mailman.205.1459344178.28225.python-list@python.org> (permalink)
References	(5 earlier) <mailman.192.1459335430.28225.python-list@python.org> <lf54mbous6w.fsf@ling.helsinki.fi> <8760w4mbr3.fsf@elektro.pacujo.net> <mailman.196.1459340966.28225.python-list@python.org> <87wpokktw5.fsf@elektro.pacujo.net>

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On 03/30/16 at 03:55pm, Marko Rauhamaa wrote:
> Manolo Martínez <manolo@austrohungaro.com>:
> 
> > On 03/30/16 at 02:44pm, Marko Rauhamaa wrote:
> >> I don't even know if you can say much about the cardinality (or
> >> countability) of mappings. The general set of mappings can't exist.
> >> The *class* of mappings does exist in some set theories, but I don't
> >> believe classes have cardinality.
> >
> > I guess I was thinking of the cardinality of the set of tuples with
> > members of the domain in the first member and their image in the
> > second.
> 
> If you fix the domain and codomain, then we can discuss cardinality
> again, but the answer depends on the domain and codomain. For example,
> if the domain is the empty set, there exists precisely one function. And
> if the codomain is the empty set as well, that function is a bijection.

Yeah, what I said and you quote above is wrong: I was thinking of the
cardinality of the set of those sets of tuples. This seems like the kind
of thing that would result in set-theoretic paradoxes, so yes, you are
probably right that the cardinality of mappings is not well defined.

Manolo

Thread

Re: Suggestion: make sequence and map interfaces more similar "Marco S." <mail.python.org@marco.sulla.e4ward.com> - 2016-03-27 20:01 +0200
  Re: Suggestion: make sequence and map interfaces more similar Steven D'Aprano <steve@pearwood.info> - 2016-03-28 12:05 +1100
    Re: Suggestion: make sequence and map interfaces more similar Antoon Pardon <antoon.pardon@rece.vub.ac.be> - 2016-03-29 16:08 +0200
    Re: Suggestion: make sequence and map interfaces more similar Chris Angelico <rosuav@gmail.com> - 2016-03-30 01:31 +1100
    Re: Suggestion: make sequence and map interfaces more similar Marco Sulla <mail.python.org@marco.sulla.e4ward.com> - 2016-03-30 00:29 +0200
    Re: Suggestion: make sequence and map interfaces more similar Terry Reedy <tjreedy@udel.edu> - 2016-03-29 20:55 -0400
    Re: Suggestion: make sequence and map interfaces more similar Chris Angelico <rosuav@gmail.com> - 2016-03-30 11:56 +1100
    Re: Suggestion: make sequence and map interfaces more similar Random832 <random832@fastmail.com> - 2016-03-29 23:38 -0400
      Re: Suggestion: make sequence and map interfaces more similar Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2016-03-30 16:43 +1100
        Re: Suggestion: make sequence and map interfaces more similar Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2016-03-30 16:57 +1100
        Re: Suggestion: make sequence and map interfaces more similar Jussi Piitulainen <jussi.piitulainen@helsinki.fi> - 2016-03-30 10:12 +0300
          Re: Suggestion: make sequence and map interfaces more similar Steven D'Aprano <steve@pearwood.info> - 2016-03-30 21:17 +1100
            Re: Suggestion: make sequence and map interfaces more similar Jussi Piitulainen <jussi.piitulainen@helsinki.fi> - 2016-03-30 13:28 +0300
              Re: Suggestion: make sequence and map interfaces more similar Antoon Pardon <antoon.pardon@rece.vub.ac.be> - 2016-03-30 12:34 +0200
                Re: Suggestion: make sequence and map interfaces more similar Jussi Piitulainen <jussi.piitulainen@helsinki.fi> - 2016-03-30 13:57 +0300
              Re: Suggestion: make sequence and map interfaces more similar Steven D'Aprano <steve@pearwood.info> - 2016-03-30 23:22 +1100
                Re: Suggestion: make sequence and map interfaces more similar Antoon Pardon <antoon.pardon@rece.vub.ac.be> - 2016-03-30 15:12 +0200
                Re: Suggestion: make sequence and map interfaces more similar Steven D'Aprano <steve@pearwood.info> - 2016-03-31 02:56 +1100
                Re: Suggestion: make sequence and map interfaces more similar Antoon Pardon <antoon.pardon@rece.vub.ac.be> - 2016-03-30 21:07 +0200
                Re: Suggestion: make sequence and map interfaces more similar Steven D'Aprano <steve@pearwood.info> - 2016-03-31 13:40 +1100
                Re: Suggestion: make sequence and map interfaces more similar Paul Rubin <no.email@nospam.invalid> - 2016-03-30 19:45 -0700
                Re: Suggestion: make sequence and map interfaces more similar Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2016-03-31 17:45 +1100
                Re: Suggestion: make sequence and map interfaces more similar Antoon Pardon <antoon.pardon@rece.vub.ac.be> - 2016-03-31 09:52 +0200
                Re: Suggestion: make sequence and map interfaces more similar Steven D'Aprano <steve@pearwood.info> - 2016-03-31 21:36 +1100
                Re: Suggestion: make sequence and map interfaces more similar Antoon Pardon <antoon.pardon@rece.vub.ac.be> - 2016-03-31 12:51 +0200
                Re: Suggestion: make sequence and map interfaces more similar Antoon Pardon <antoon.pardon@rece.vub.ac.be> - 2016-03-31 13:22 +0200
                Re: Suggestion: make sequence and map interfaces more similar Chris Angelico <rosuav@gmail.com> - 2016-03-31 22:57 +1100
                Re: Suggestion: make sequence and map interfaces more similar Marko Rauhamaa <marko@pacujo.net> - 2016-03-31 15:36 +0300
                Re: Suggestion: make sequence and map interfaces more similar Chris Angelico <rosuav@gmail.com> - 2016-03-31 23:48 +1100
                Re: Suggestion: make sequence and map interfaces more similar Marko Rauhamaa <marko@pacujo.net> - 2016-03-31 17:02 +0300
                Re: Suggestion: make sequence and map interfaces more similar Michael Selik <michael.selik@gmail.com> - 2016-04-01 04:19 -0400
                Re: Suggestion: make sequence and map interfaces more similar Jussi Piitulainen <jussi.piitulainen@helsinki.fi> - 2016-03-31 15:55 +0300
                Re: Suggestion: make sequence and map interfaces more similar Marko Rauhamaa <marko@pacujo.net> - 2016-03-31 17:19 +0300
                Re: Suggestion: make sequence and map interfaces more similar Antoon Pardon <antoon.pardon@rece.vub.ac.be> - 2016-03-31 15:08 +0200
                Re: Suggestion: make sequence and map interfaces more similar Rustom Mody <rustompmody@gmail.com> - 2016-03-31 06:42 -0700
                Re: Suggestion: make sequence and map interfaces more similar Chris Angelico <rosuav@gmail.com> - 2016-04-01 00:11 +1100
                Re: Suggestion: make sequence and map interfaces more similar Mark Lawrence <breamoreboy@yahoo.co.uk> - 2016-03-31 14:17 +0100
                Re: Suggestion: make sequence and map interfaces more similar Random832 <random832@fastmail.com> - 2016-03-31 09:27 -0400
                Re: Suggestion: make sequence and map interfaces more similar Marko Rauhamaa <marko@pacujo.net> - 2016-03-31 17:13 +0300
                Re: Suggestion: make sequence and map interfaces more similar Terry Reedy <tjreedy@udel.edu> - 2016-03-31 13:41 -0400
                Re: Suggestion: make sequence and map interfaces more similar Mark Lawrence <breamoreboy@yahoo.co.uk> - 2016-03-31 15:12 +0100
                Re: Suggestion: make sequence and map interfaces more similar Antoon Pardon <antoon.pardon@rece.vub.ac.be> - 2016-04-01 09:59 +0200
                Re: Suggestion: make sequence and map interfaces more similar Tim Golden <mail@timgolden.me.uk> - 2016-04-01 09:27 +0100
                Re: Suggestion: make sequence and map interfaces more similar Steven D'Aprano <steve@pearwood.info> - 2016-04-01 21:38 +1100
                Re: Suggestion: make sequence and map interfaces more similar Marko Rauhamaa <marko@pacujo.net> - 2016-04-01 13:50 +0300
                Re: Suggestion: make sequence and map interfaces more similar Rustom Mody <rustompmody@gmail.com> - 2016-04-01 07:41 -0700
                Re: Suggestion: make sequence and map interfaces more similar Mark Lawrence <breamoreboy@yahoo.co.uk> - 2016-04-01 10:04 +0100
                Re: Suggestion: make sequence and map interfaces more similar Marco Sulla <mail.python.org@marco.sulla.e4ward.com> - 2016-03-30 21:35 +0200
                Re: Suggestion: make sequence and map interfaces more similar Mark Lawrence <breamoreboy@yahoo.co.uk> - 2016-03-30 21:31 +0100
            Re: Suggestion: make sequence and map interfaces more similar Manolo Martínez <manolo@austrohungaro.com> - 2016-03-30 12:26 +0200
              Re: Suggestion: make sequence and map interfaces more similar Jussi Piitulainen <jussi.piitulainen@helsinki.fi> - 2016-03-30 13:40 +0300
                Re: Suggestion: make sequence and map interfaces more similar Manolo Martínez <manolo@austrohungaro.com> - 2016-03-30 12:50 +0200
                Re: Suggestion: make sequence and map interfaces more similar Jussi Piitulainen <jussi.piitulainen@helsinki.fi> - 2016-03-30 14:21 +0300
                Re: Suggestion: make sequence and map interfaces more similar Marko Rauhamaa <marko@pacujo.net> - 2016-03-30 14:44 +0300
                Re: Suggestion: make sequence and map interfaces more similar Manolo Martínez <manolo@austrohungaro.com> - 2016-03-30 14:29 +0200
                Re: Suggestion: make sequence and map interfaces more similar Marko Rauhamaa <marko@pacujo.net> - 2016-03-30 15:55 +0300
                Re: Suggestion: make sequence and map interfaces more similar Manolo Martínez <manolo@austrohungaro.com> - 2016-03-30 15:13 +0200
                Re: Suggestion: make sequence and map interfaces more similar Steven D'Aprano <steve@pearwood.info> - 2016-03-30 23:27 +1100
                Re: Suggestion: make sequence and map interfaces more similar Marko Rauhamaa <marko@pacujo.net> - 2016-03-30 15:48 +0300
                Re: Suggestion: make sequence and map interfaces more similar Jussi Piitulainen <jussi.piitulainen@helsinki.fi> - 2016-03-30 17:38 +0300
                Re: Suggestion: make sequence and map interfaces more similar Jussi Piitulainen <jussi.piitulainen@helsinki.fi> - 2016-03-30 17:25 +0300
        Re: Suggestion: make sequence and map interfaces more similar Antoon Pardon <antoon.pardon@rece.vub.ac.be> - 2016-03-30 10:55 +0200
        Re: Suggestion: make sequence and map interfaces more similar Random832 <random832@fastmail.com> - 2016-03-30 08:50 -0400
          Re: Suggestion: make sequence and map interfaces more similar Steven D'Aprano <steve@pearwood.info> - 2016-03-31 03:02 +1100
            Re: Suggestion: make sequence and map interfaces more similar Random832 <random832@fastmail.com> - 2016-03-30 12:52 -0400
              Re: Suggestion: make sequence and map interfaces more similar Steven D'Aprano <steve@pearwood.info> - 2016-03-31 13:44 +1100
                Re: Suggestion: make sequence and map interfaces more similar Antoon Pardon <antoon.pardon@rece.vub.ac.be> - 2016-03-31 10:04 +0200
                Re: Suggestion: make sequence and map interfaces more similar Marco Sulla <mail.python.org@marco.sulla.e4ward.com> - 2016-03-31 13:58 +0200
                Re: Suggestion: make sequence and map interfaces more similar Mark Lawrence <breamoreboy@yahoo.co.uk> - 2016-03-31 13:30 +0100
                Re: Suggestion: make sequence and map interfaces more similar Marco Sulla <mail.python.org@marco.sulla.e4ward.com> - 2016-03-31 14:49 +0200
                Re: Suggestion: make sequence and map interfaces more similar Mark Lawrence <breamoreboy@yahoo.co.uk> - 2016-03-31 14:14 +0100
            Re: Suggestion: make sequence and map interfaces more similar Marco Sulla <mail.python.org@marco.sulla.e4ward.com> - 2016-03-30 22:00 +0200
            Re: Suggestion: make sequence and map interfaces more similar Mark Lawrence <breamoreboy@yahoo.co.uk> - 2016-03-30 21:36 +0100
    Re: Suggestion: make sequence and map interfaces more similar Mark Lawrence <breamoreboy@yahoo.co.uk> - 2016-03-30 08:03 +0100

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