leap

elixir/leap/lib/year.ex

@@ -0,0 +1,16 @@
+defmodule Year do
+  @doc """
+  Returns whether 'year' is a leap year.
+
+  A leap year occurs:
+
+  on every year that is evenly divisible by 4
+    except every year that is evenly divisible by 100
+      unless the year is also evenly divisible by 400
+  """
+  @spec leap_year?(non_neg_integer) :: boolean
+  def leap_year?(year) when rem(year, 400) == 0, do: true
+  def leap_year?(year) when rem(year, 100) == 0, do: false
+  def leap_year?(year) when rem(year, 4) == 0, do: true
+  def leap_year?(_year), do: false
+end