Add recursive approach from the elixir-book

control/fizzbuzz.ex

@@ -5,7 +5,7 @@ defmodule FizzBuzz do
     |> Enum.map(&FizzBuzz.check/1)
   end
 
-  def check(number) do
+  def check(number) when number > 0 do
     cond do
       rem(number, 5) == 0 and rem(number, 3) == 0 ->
         "Fizzbuzz!"
@@ -18,3 +18,24 @@ defmodule FizzBuzz do
     end
   end
 end
+
+defmodule RecursiveFizzBuzz do
+  def upto(n) when n > 0, do: _upto(1, n, [])
+
+  defp _upto(_current, 0, result), do: Enum.reverse result
+
+  defp _upto(current, left, result) do
+    next_answer = 
+      cond do
+        rem(current, 3) == 0 and rem(current, 5) == 0 ->
+          "Fizzbuzz!"
+        rem(current, 3) == 0 ->
+          "Fizz"
+        rem(current, 5) == 0 ->
+          "Buzz"
+        true ->
+          current
+      end
+    _upto(current+1, left-1, [next_answer | result] )
+  end
+end