gistfile1.rb

class Stream

  include Enumerable

  attr_reader :succ, :value

  def initialize(value, &block)
    @value, @succ = value, block
  end

  def next
    Stream.new(  succ.call( value ) , &succ )
  end

  def [](index)
    stream = self
    index.times{ stream = stream.next }
    stream.value
  end

  def each(&block)
    stack_safe = proc do | stream |
      block.call stream.value
      stream.next
    end
    stream = self
    loop{ stream = stack_safe.call(stream) }
  end

end

# s = Stream.new(1){ |n| n + 1 }