[ruby-dev:47392] [ruby-trunk - Bug #7877] E::Lazy#with_index should be lazy

Issue #7877 has been updated by zzak (Zachary Scott).

Tracker changed from Feature to Bug
Subject changed from E::Lazy#with_index needed to E::Lazy#with_index should be lazy
Target version changed from next minor to current: 2.1.0
ruby -v set to 2.1.0-dev
Backport set to 2.0.0: UNKNOWN


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Bug #7877: E::Lazy#with_index should be lazy
https://bugs.ruby-lang.org/issues/7877#change-39637

Author: shyouhei (Shyouhei Urabe)
Status: Assigned
Priority: Normal
Assignee: yhara (Yutaka HARA)
Category: core
Target version: current: 2.1.0
ruby -v: 2.1.0-dev
Backport: 2.0.0: UNKNOWN


=begin
So I wanted some real benefit of being lazy.  I wrote a Leibniz formula:

  def leibniz(n)
    (0..Float::INFINITY).lazy.with_index {|i, j| (-1 ** j) / (2*i+1).to_f }.take(n).reduce(:+)
  end

But it doesn't work (well, it does, indeed. It just doesn't stop working).  I got frustrated.
How about it?  Don't you feel it nifty?

Of course I can wait for the release next to 2.0.0.
=end


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