[darcien]

You can use Stream.unfold/2:

  Stream.unfold({0,1}, fn {a,b} -> {a,{b,a+b}} end)
  |> Enum.take(10)
  [0, 1, 1, 2, 3, 5, 8, 13, 21, 34]

https://rosettacode.org/wiki/Fibonacci_sequence#Elixir