From: Xavier Noria <fxn@...>
Date: 2007-09-21T08:37:40+09:00
Subject: Re: Idiomatic Ruby for Array#extract / Range#length?

Right, I've got an infinite closed Range with standard Ruby:

   class ZSquared
     include Comparable

     attr_reader :n, :m

     def initialize(n, m)
       @n, @m = n, m
     end

     def succ
       self.class.new(n+1, m)
     end

     def <=>(zs)
       self.m <=> zs.m
     end
   end

   a = ZSquared.new(0, 0)
   b = ZSquared.new(0, 1)

   puts a < b # true

   length = 0
   (a .. b).each do |c|
     length += 1
     puts length
   end

   # be prepared to send Ctrl-C

I am very sorry for the direction this thread took, I am used to  
formal stuff and used to discuss within its limits with no further  
interpretations. I knew this was possible but the first example that  
came to my head was math-based and it was not my intention to get  
into proofs and stuff which may not be clear to all people in the list.

I guess the claim that well-defined infinite Ranges in Ruby are  
implementable is now clear.

-- fxn