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Re: Something is rotten in Denmark...

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rusi writes:
> On Jun 3, 11:17 am, Jussi Piitulainen wrote:
> > rusi writes:
> > > So I tried:
> > > Recast the comprehension as a map
> > > Rewrite the map into a fmap (functionalmap) to create new bindings
> >
> > > def fmap(f,lst):
> > >     if not lst: return []
> > >     return [f(lst[0])] + fmap(f, lst[1:])
> >
> > > Still the same effects.
> >
> > > Obviously I am changing it at the wrong place...
> >
> >    >>> fs = [(lambda n : n + i) for i in range(10)]
> >    >>> [f(1) for f in fs]
> >    [10, 10, 10, 10, 10, 10, 10, 10, 10, 10]
> >
> >    >>> fs = list(map(lambda i : lambda n : n + i, range(10)))
> >    >>> list(map(lambda f : f(1), fs))
> >    [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
> 
> Thanks Jussi for that code -- but I am not fully able to wrap my head
> around it.

Oops, sorry, I seem to have edited out a question that I meant to ask.
The question was this: How do -you- write the list comprehension in
terms of your fmap? What -is- the expression that still has the same
effects? That is, where do you bind the i's?

The obvious-to-me way is shown above, but there it is the outer lambda
that establishes the distinct i's for the different closures.

(The composition list(map(...)) works in both versions of Python.)

> Is the problem in the lambda? ZF?
> Are you trying to say that map works (functionally) and ZF is
> imperative?

Sorry, what is ZF?

I'm saying that your fmap works, but in itself it does not provide the
bindings that we are talking about, and you didn't show what does. The
outer lambda in my example does that.

The Python list comprehension [... for i in ...] binds (or assigns to)
just one i which is shared by all the closures above. They end up
having the same value for i because it's the same i.

I hope this is less obscure now.

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Thread

Something is rotten in Denmark... harrismh777 <harrismh777@charter.net> - 2011-05-31 01:48 -0500
  Re: Something is rotten in Denmark... Chris Rebert <clp2@rebertia.com> - 2011-05-31 00:00 -0700
  Re: Something is rotten in Denmark... Ian Kelly <ian.g.kelly@gmail.com> - 2011-05-31 01:35 -0600
  Re: Something is rotten in Denmark... Jussi Piitulainen <jpiitula@ling.helsinki.fi> - 2011-05-31 13:08 +0300
    Re: Something is rotten in Denmark... Thomas Rachel <nutznetz-0c1b6768-bfa9-48d5-a470-7603bd3aa915@spamschutz.glglgl.de> - 2011-05-31 12:48 +0200
      Re: Something is rotten in Denmark... Jussi Piitulainen <jpiitula@ling.helsinki.fi> - 2011-05-31 15:15 +0300
  Re: Something is rotten in Denmark... Terry Reedy <tjreedy@udel.edu> - 2011-05-31 13:11 -0400
    Re: Something is rotten in Denmark... harrismh777 <harrismh777@charter.net> - 2011-05-31 15:18 -0500
      Re: Something is rotten in Denmark... Ian Kelly <ian.g.kelly@gmail.com> - 2011-05-31 16:24 -0600
      Re: Something is rotten in Denmark... Terry Reedy <tjreedy@udel.edu> - 2011-05-31 19:14 -0400
        Re: Something is rotten in Denmark... harrismh777 <harrismh777@charter.net> - 2011-05-31 19:09 -0500
          Re: Something is rotten in Denmark... Terry Reedy <tjreedy@udel.edu> - 2011-06-01 13:11 -0400
            Re: Something is rotten in Denmark... harrismh777 <harrismh777@charter.net> - 2011-06-01 19:40 -0500
              Re: Something is rotten in Denmark... harrismh777 <harrismh777@charter.net> - 2011-06-01 19:50 -0500
                Re: Something is rotten in Denmark... Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2011-06-02 04:37 +0000
              Re: Something is rotten in Denmark... Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2011-06-02 05:14 +0000
                Re: Something is rotten in Denmark... Chris Angelico <rosuav@gmail.com> - 2011-06-02 18:02 +1000
                Re: Something is rotten in Denmark... Alain Ketterlin <alain@dpt-info.u-strasbg.fr> - 2011-06-02 13:00 +0200
                Re: Something is rotten in Denmark... Jussi Piitulainen <jpiitula@ling.helsinki.fi> - 2011-06-02 15:51 +0300
                Re: Something is rotten in Denmark... Terry Reedy <tjreedy@udel.edu> - 2011-06-02 15:43 -0400
                Re: Something is rotten in Denmark... Gregory Ewing <greg.ewing@canterbury.ac.nz> - 2011-06-03 11:43 +1200
                Re: Something is rotten in Denmark... rusi <rustompmody@gmail.com> - 2011-06-02 19:24 -0700
                Re: Something is rotten in Denmark... Jussi Piitulainen <jpiitula@ling.helsinki.fi> - 2011-06-03 09:17 +0300
                Re: Something is rotten in Denmark... rusi <rustompmody@gmail.com> - 2011-06-05 03:54 -0700
                Re: Something is rotten in Denmark... Jussi Piitulainen <jpiitula@ling.helsinki.fi> - 2011-06-05 15:03 +0300
                Re: Something is rotten in Denmark... rusi <rustompmody@gmail.com> - 2011-06-05 05:26 -0700
                Re: Something is rotten in Denmark... Jussi Piitulainen <jpiitula@ling.helsinki.fi> - 2011-06-05 16:10 +0300
                Re: Something is rotten in Denmark... Thomas Rachel <nutznetz-0c1b6768-bfa9-48d5-a470-7603bd3aa915@spamschutz.glglgl.de> - 2011-06-03 10:30 +0200
                Re: Something is rotten in Denmark... Ian Kelly <ian.g.kelly@gmail.com> - 2011-06-03 11:53 -0600
                Re: Something is rotten in Denmark... Alain Ketterlin <alain@dpt-info.u-strasbg.fr> - 2011-06-03 12:35 +0200
                Re: Something is rotten in Denmark... Jussi Piitulainen <jpiitula@ling.helsinki.fi> - 2011-06-03 14:07 +0300
                Re: Something is rotten in Denmark... harrismh777 <harrismh777@charter.net> - 2011-06-03 15:38 -0500
                Re: Something is rotten in Denmark... Gregory Ewing <greg.ewing@canterbury.ac.nz> - 2011-06-04 12:40 +1200
                Re: Something is rotten in Denmark... Nobody <nobody@nowhere.com> - 2011-06-03 14:07 +0100
                Re: Something is rotten in Denmark... harrismh777 <harrismh777@charter.net> - 2011-06-02 10:44 -0500
                Re: Something is rotten in Denmark... harrismh777 <harrismh777@charter.net> - 2011-06-02 10:55 -0500
                Re: Something is rotten in Denmark... Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2011-06-02 17:22 +0000
                Re: Something is rotten in Denmark... Ian Kelly <ian.g.kelly@gmail.com> - 2011-06-02 11:43 -0600
              Re: Something is rotten in Denmark... Terry Reedy <tjreedy@udel.edu> - 2011-06-02 02:02 -0400
                Re: Something is rotten in Denmark... harrismh777 <harrismh777@charter.net> - 2011-06-02 11:02 -0500
  Re: Something is rotten in Denmark... Martin Manns <mmanns@gmx.net> - 2011-05-31 23:14 +0200
    Re: Something is rotten in Denmark... Ian Kelly <ian.g.kelly@gmail.com> - 2011-05-31 15:47 -0600
      Re: Something is rotten in Denmark... Martin Manns <mmanns@gmx.net> - 2011-06-01 02:57 +0200
    Re: Something is rotten in Denmark... harrismh777 <harrismh777@charter.net> - 2011-05-31 16:53 -0500
      Re: Something is rotten in Denmark... harrismh777 <harrismh777@charter.net> - 2011-05-31 17:06 -0500
      Re: Something is rotten in Denmark... Chris Angelico <rosuav@gmail.com> - 2011-06-01 08:39 +1000
      Re: Something is rotten in Denmark... Chris Angelico <rosuav@gmail.com> - 2011-06-01 08:40 +1000

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