First commit

geometry.ex

@@ -0,0 +1,30 @@
+defmodule Geometry do
+  def rectangle_area(a, b) do
+    a * b
+  end
+
+  def rectangle_area_condensed(a, b), do: a * b
+end
+
+defmodule Rectangle do
+  def area(a, b), do: a * b
+  def area(a), do: area(a, a)
+end
+
+defmodule GeometryMultiClause do
+  def area({:rectangle, a, b}) do
+    a * b
+  end
+
+  def area({:square, a}) do
+    a * a
+  end
+
+  def area({:circle, r}) do
+    r * r * 3.14159
+  end
+
+  def area(unknown) do
+    {:error, {:unkown_shape, unknown}}
+  end
+end