From 933e11acb9cca432b54e1050b616175b20cfb832 Mon Sep 17 00:00:00 2001
From: Uku Taht <uku.taht@gmail.com>
Date: Wed, 13 Jan 2016 13:31:04 +0000
Subject: [PATCH] Intercept and print compile errors in a nicer way.

---
 lib/display.ex | 5 +++++
 lib/watcher.ex | 8 ++++++--
 2 files changed, 11 insertions(+), 2 deletions(-)

diff --git a/lib/display.ex b/lib/display.ex
index 7c64c0f..7b58519 100644
--- a/lib/display.ex
+++ b/lib/display.ex
@@ -24,6 +24,11 @@ defmodule Display do
     "Assertion failed in #{source_file(module)}:#{line_number(expr)}"
   end
 
+  def format_compile_error(error) do
+    trace = System.stacktrace |> Enum.take(2)
+    IO.puts(format_red(Exception.format(:error, error, trace)))
+  end
+
   defp line_number({_, [line: line], _}) do
     line
   end
diff --git a/lib/watcher.ex b/lib/watcher.ex
index ce1baef..a33cdeb 100644
--- a/lib/watcher.ex
+++ b/lib/watcher.ex
@@ -3,8 +3,12 @@ defmodule Watcher do
 
   def callback(file, events)  do
     if Enum.member?(events, :modified) do
-      [{mod, _}] = Code.load_file(file)
-      Runner.run(mod)
+      try do
+        [{mod, _}] = Code.load_file(file)
+        Runner.run(mod)
+      rescue
+        e -> Display.format_compile_error(e)
+      end
     end
   end
 end