Default mix task should be run, closes #834

Author: José Valim

lib/mix/lib/mix/cli.ex

@@ -34,7 +34,7 @@ defmodule Mix.CLI do
   end
 
   defp get_task([]) do
-    { Mix.project[:default_task] || "compile", [] }
+    { Mix.project[:default_task] || "run", [] }
   end
 
   defp run_task(name, args) do

lib/mix/lib/mix/project.ex

@@ -131,7 +131,7 @@ defmodule Mix.Project do
     [ compile_path: "ebin",
       elixirc_exts: [:ex],
       default_env: [test: :test],
-      default_task: "compile",
+      default_task: "run",
       deps_path: "deps",
       erlc_paths: ["src"],
       lockfile: "mix.lock",

lib/mix/lib/mix/tasks/run.ex

@@ -39,8 +39,7 @@ defmodule Mix.Tasks.Run do
     end
 
     Mix.Task.run Mix.project[:prepare_task], args
-    Code.eval Enum.join(head, " ")
-
+    if head != [], do: Code.eval Enum.join(head, " ")
     if opts[:no_halt], do: :timer.sleep(:infinity)
   end