lucas-numbers

elixir/lucas-numbers/lib/lucas_numbers.ex

@@ -0,0 +1,17 @@
+defmodule LucasNumbers do
+  @moduledoc """
+  Lucas numbers are an infinite sequence of numbers which build progressively
+  which hold a strong correlation to the golden ratio (φ or ϕ)
+
+  E.g.: 2, 1, 3, 4, 7, 11, 18, 29, ...
+  """
+
+  def generate(count) when is_integer(count) and count > 0 do
+    {2, 1}
+    |> Stream.iterate(fn {a, b} -> {b, a + b} end)
+    |> Stream.map(&elem(&1, 0))
+    |> Enum.take(count)
+  end
+
+  def generate(_count), do: raise(ArgumentError, "count must be specified as an integer >= 1")
+end