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Re: anonymous closures with Proc,new, lambda and ->

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Stu wrote in post #993687:
> I am new to the study of functional paradigm. If this question is
> academic
> please bear with me.
>
> How would I make this counter with lambda or -> without deferring to a
> named
> generator method or sigil var?

Starting with the "named generator method":

def make_counter(init)
  lambda { init += 1 }
end

Calling that method creates a new scope, and binds the value of 'init' 
within that scope.

Now, you can do the same without def, by wrapping in another lambda:

counter_maker = lambda { |init| lambda { init += 1 } }
c = counter_maker.call(100)
c.call  # 101
c.call  # 102

And you can do the same without explicitly binding 'counter_maker' 
either:

c = lambda { |init| lambda { init += 1 } }.call(200)
c.call  # 201
c.call  # 202

Is that what you were looking for?

-- 
Posted via http://www.ruby-forum.com/.

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anonymous closures with Proc,new, lambda and -> Stu <stu@rubyprogrammer.net> - 2011-04-19 01:07 -0500
  Re: anonymous closures with Proc,new, lambda and -> Robert Klemme <shortcutter@googlemail.com> - 2011-04-19 02:30 -0500
  Re: anonymous closures with Proc,new, lambda and -> Brian Candler <b.candler@pobox.com> - 2011-04-19 03:05 -0500
    Re: anonymous closures with Proc,new, lambda and -> Brian Candler <b.candler@pobox.com> - 2011-04-19 03:15 -0500
      Re: anonymous closures with Proc,new, lambda and -> Stu <stu@rubyprogrammer.net> - 2011-04-19 04:57 -0500
        Re: anonymous closures with Proc,new, lambda and -> Brian Candler <b.candler@pobox.com> - 2011-04-19 07:24 -0500
          Re: anonymous closures with Proc,new, lambda and -> Adam Prescott <adam@aprescott.com> - 2011-04-19 14:55 -0500
      Re: anonymous closures with Proc,new, lambda and -> Stu <stu@rubyprogrammer.net> - 2011-04-19 16:43 -0500
        Re: anonymous closures with Proc,new, lambda and -> 7stud -- <bbxx789_05ss@yahoo.com> - 2011-04-19 18:48 -0500
        Re: anonymous closures with Proc,new, lambda and -> 7stud -- <bbxx789_05ss@yahoo.com> - 2011-04-19 21:28 -0500
          Re: anonymous closures with Proc,new, lambda and -> Stu <stu@rubyprogrammer.net> - 2011-04-20 01:03 -0500
            Re: anonymous closures with Proc,new, lambda and -> Robert Klemme <shortcutter@googlemail.com> - 2011-04-20 02:23 -0500
              Re: anonymous closures with Proc,new, lambda and -> Steve Klabnik <steve@steveklabnik.com> - 2011-04-20 05:55 -0500
            Re: anonymous closures with Proc,new, lambda and -> 7stud -- <bbxx789_05ss@yahoo.com> - 2011-04-20 12:32 -0500
              Re: anonymous closures with Proc,new, lambda and -> Steve Klabnik <steve@steveklabnik.com> - 2011-04-20 12:59 -0500
                Re: anonymous closures with Proc,new, lambda and -> Brian Candler <b.candler@pobox.com> - 2011-04-20 15:40 -0500
                Re: anonymous closures with Proc,new, lambda and -> 7stud -- <bbxx789_05ss@yahoo.com> - 2011-04-20 19:51 -0500
                Re: anonymous closures with Proc,new, lambda and -> Stu <stu@rubyprogrammer.net> - 2011-04-21 01:31 -0500
                Re: anonymous closures with Proc,new, lambda and -> Brian Candler <b.candler@pobox.com> - 2011-04-21 04:34 -0500
                Re: anonymous closures with Proc,new, lambda and -> Robert Klemme <shortcutter@googlemail.com> - 2011-04-21 06:13 -0500
                Re: anonymous closures with Proc,new, lambda and -> Robert Klemme <shortcutter@googlemail.com> - 2011-04-21 09:20 -0500
                Re: anonymous closures with Proc,new, lambda and -> 7stud -- <bbxx789_05ss@yahoo.com> - 2011-04-21 11:56 -0500
                Re: anonymous closures with Proc,new, lambda and -> Steve Klabnik <steve@steveklabnik.com> - 2011-04-21 12:06 -0500
                Re: anonymous closures with Proc,new, lambda and -> Robert Klemme <shortcutter@googlemail.com> - 2011-04-27 06:49 -0500
                Re: anonymous closures with Proc,new, lambda and -> Stu <stu@rubyprogrammer.net> - 2011-04-27 13:33 -0500
                Re: anonymous closures with Proc,new, lambda and -> Steve Klabnik <steve@steveklabnik.com> - 2011-04-27 17:06 -0500
  Re: anonymous closures with Proc,new, lambda and -> 7stud -- <bbxx789_05ss@yahoo.com> - 2011-04-19 13:02 -0500
    Re: anonymous closures with Proc,new, lambda and -> Brian Candler <b.candler@pobox.com> - 2011-04-19 13:19 -0500
      Re: anonymous closures with Proc,new, lambda and -> Steve Klabnik <steve@steveklabnik.com> - 2011-04-19 13:26 -0500
        Re: anonymous closures with Proc,new, lambda and -> Michael Edgar <adgar@carboni.ca> - 2011-04-19 13:51 -0500
          Re: anonymous closures with Proc,new, lambda and -> Brian Candler <b.candler@pobox.com> - 2011-04-20 10:18 -0500
            Re: anonymous closures with Proc,new, lambda and -> Jeremy Bopp <jeremy@bopp.net> - 2011-04-20 12:44 -0500

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