streamy.ex

defmodule Streamy do
  def start do
    start = fn -> 0 end
    next = fn value -> {[value + 1], value + 1} end
    stop = fn value -> value end
    Stream.resource(start, next, stop)
  end
end

require Integer

Streamy.start()
|> Stream.filter(&Integer.is_even/1)
|> Stream.map(&"#{&1}... ")
|> Enum.take(5)
|> IO.puts()
# This returns 2... 4... 6... 8... 10...
# If we want 0 to be included the start function should return -1.
# This is because only the elements in the list which is returned in the next function tuple are Streamed.