First rough cut on ANSI escaping

lib/apex/format/color.ex

@@ -0,0 +1,19 @@
+defmodule Apex.Format.Color do
+
+  def colorize(text, data) do
+    if color = color(data) do
+      escape(text, color)
+    else
+      text
+    end
+  end
+
+  defp color(data) when is_list(data),   do: "yellow"
+  defp color(data) when is_tuple(data),  do: "blue"
+  defp color(data) when is_binary(data), do: "red"
+  defp color(data), do: nil
+
+  defp escape(text, color) do
+    IO.ANSI.escape_fragment("%{#{color}}") <> text <> IO.ANSI.escape_fragment("%{reset}")
+  end
+end

lib/apex/format/utils.ex

@@ -4,6 +4,14 @@ defmodule Apex.Format.Utils do
 
   def new_line, do: "\n"
 
+  def colorize(str, data, options) do
+    if options[:color] == false do
+      str
+    else
+      Apex.Format.Color.colorize(str, data)
+    end
+  end
+
   def next_indent_level(options) do
     Keyword.update(options, :indent_level, 1, &( &1 + 1))
   end

test/format/color_test.ex

@@ -0,0 +1,8 @@
+defmodule Apex.Format.Color.Test do
+  use ExUnit.Case
+  import Apex.Format.Color
+
+  test "#colorize should color text based on the type" do
+    assert colorize("Tuple should be yellow", {}) == "\e[34mTuple should be yellow\e[0m"
+  end
+end

test/format/utils_test.exs

@@ -21,4 +21,8 @@ defmodule Apex.Format.Utils.Test do
     assert indent([indent_level: 2, indent: 1]) == "  "
     assert indent([indent_level: 3, indent: 1]) == "   "
   end
+
+  test "#colorize should not do anything when it's turned off" do
+    assert colorize("FOO", {}, color: false) == "FOO"
+  end
 end