A naive ruby port of my lisp code for implementing streams.

streams.rb

class EvenStream
  attr_reader :value

  def initialize(n = 0)
    @value = n
    @next = lambda { EvenStream.new(n + 2) }
  end

  def next
    @next.call
  end
end

class FibonacciStream
  attr_reader :value

  def initialize(previous = 1, value = 1)
    @previous = previous
    @value = value
    @next = lambda { FibonacciStream.new(value, previous + value) }
  end

  def next
    @next.call
  end
end

e = FibonacciStream.new
10.times do
  p e.value
  e = e.next
end