diff --git a/lib/mix/lib/mix/tasks/compile.app.ex b/lib/mix/lib/mix/tasks/compile.app.ex
index 69a250b4857..6f8fd144f43 100644
--- a/lib/mix/lib/mix/tasks/compile.app.ex
+++ b/lib/mix/lib/mix/tasks/compile.app.ex
@@ -107,45 +107,50 @@ defmodule Mix.Tasks.Compile.App do
   def run(args) do
     {opts, _, _} = OptionParser.parse(args, switches: [force: :boolean])
 
-    project = Mix.Project.get!
-    config  = Mix.Project.config
+    project = Mix.Project.get!()
+    config = Mix.Project.config()
 
-    app     = Keyword.get(config, :app)
+    app = Keyword.get(config, :app)
     version = Keyword.get(config, :version)
 
     validate_app(app)
     validate_version(version)
 
-    path = Mix.Project.compile_path
-    mods = modules_from(Path.wildcard("#{path}/*.beam")) |> Enum.sort
+    path = Mix.Project.compile_path()
+    mods = modules_from(Path.wildcard("#{path}/*.beam")) |> Enum.sort()
 
-    target  = Path.join(path, "#{app}.app")
-    sources = Mix.Project.config_files
+    target = Path.join(path, "#{app}.app")
+    sources = Mix.Project.config_files()
 
     if opts[:force] || Mix.Utils.stale?(sources, [target]) || modules_changed?(mods, target) do
       best_guess = [
         description: to_charlist(config[:description] || app),
         modules: mods,
         registered: [],
-        vsn: to_charlist(version),
+        vsn: to_charlist(version)
       ]
 
-      properties = if function_exported?(project, :application, 0) do
-        project_application = project.application()
-        unless Keyword.keyword?(project_application) do
-          Mix.raise "Application configuration returned from application/0 should be a keyword list"
+      properties =
+        if function_exported?(project, :application, 0) do
+          project_application = project.application
+
+          unless Keyword.keyword?(project_application) do
+            Mix.raise(
+              "Application configuration returned from application/0 should be a keyword list"
+            )
+          end
+
+          Keyword.merge(best_guess, project_application)
+        else
+          best_guess
         end
-        Keyword.merge(best_guess, project_application)
-      else
-        best_guess
-      end
 
       properties = ensure_correct_properties(properties, config)
       contents = :io_lib.format("~p.~n", [{:application, app, properties}])
 
       Mix.Project.ensure_structure()
       File.write!(target, IO.chardata_to_string(contents))
-      Mix.shell.info "Generated #{app} app"
+      Mix.shell().info("Generated #{app} app")
       :ok
     else
       :noop
@@ -156,12 +161,14 @@ defmodule Mix.Tasks.Compile.App do
     case :file.consult(target) do
       {:ok, [{:application, _app, properties}]} ->
         properties[:modules] != mods
+
       _ ->
         false
     end
   end
 
   defp validate_app(app) when is_atom(app), do: :ok
+
   defp validate_app(app) do
     ensure_present(:app, app)
     Mix.raise("Expected :app to be an atom, got: #{inspect(app)}")
@@ -169,6 +176,7 @@ defmodule Mix.Tasks.Compile.App do
 
   defp validate_version(version) do
     ensure_present(:version, version)
+
     unless is_binary(version) and match?({:ok, _}, Version.parse(version)) do
       Mix.raise("Expected :version to be a SemVer version, got: #{inspect(version)}")
     end
@@ -177,10 +185,11 @@ defmodule Mix.Tasks.Compile.App do
   defp ensure_present(name, nil) do
     Mix.raise("Please ensure mix.exs file has the #{inspect(name)} in the project definition")
   end
+
   defp ensure_present(_name, _val), do: :ok
 
   defp modules_from(beams) do
-    Enum.map beams, &(&1 |> Path.basename |> Path.rootname(".beam") |> String.to_atom)
+    Enum.map(beams, &(&1 |> Path.basename() |> Path.rootname(".beam") |> String.to_atom()))
   end
 
   defp language_app(config) do
@@ -199,60 +208,103 @@ defmodule Mix.Tasks.Compile.App do
   end
 
   defp validate_properties!(properties) do
-    Enum.each properties, fn
+    Enum.each(properties, fn
       {:description, value} ->
         unless is_list(value) do
-          Mix.raise "Application description (:description) is not a character list, got: #{inspect value}"
+          Mix.raise(
+            "Application description (:description) is not a character list, got: #{
+              inspect(value)
+            }"
+          )
         end
+
       {:id, value} ->
         unless is_list(value) do
-          Mix.raise "Application id (:id) is not a character list, got: #{inspect value}"
+          Mix.raise("Application id (:id) is not a character list, got: #{inspect(value)}")
         end
+
       {:vsn, value} ->
         unless is_list(value) do
-          Mix.raise "Application vsn (:vsn) is not a character list, got: #{inspect value}"
+          Mix.raise("Application vsn (:vsn) is not a character list, got: #{inspect(value)}")
         end
+
       {:maxT, value} ->
         unless value == :infinity or is_integer(value) do
-          Mix.raise "Application maximum time (:maxT) is not an integer or :infinity, got: #{inspect value}"
+          Mix.raise(
+            "Application maximum time (:maxT) is not an integer or :infinity, got: " <>
+              inspect(value)
+          )
         end
+
       {:modules, value} ->
         unless is_list(value) and Enum.all?(value, &is_atom(&1)) do
-          Mix.raise "Application modules (:modules) should be a list of atoms, got: #{inspect value}"
+          Mix.raise(
+            "Application modules (:modules) should be a list of atoms, got: #{inspect(value)}"
+          )
         end
+
       {:registered, value} ->
         unless is_list(value) and Enum.all?(value, &is_atom(&1)) do
-          Mix.raise "Application registered processes (:registered) should be a list of atoms, got: #{inspect value}"
+          Mix.raise(
+            "Application registered processes (:registered) should be a list of atoms, got: " <>
+              inspect(value)
+          )
         end
+
       {:included_applications, value} ->
         unless is_list(value) and Enum.all?(value, &is_atom(&1)) do
-          Mix.raise "Application included applications (:included_applications) should be a list of atoms, got: #{inspect value}"
+          Mix.raise(
+            "Application included applications (:included_applications) should be a list of atoms, got: " <>
+              inspect(value)
+          )
         end
+
       {:extra_applications, value} ->
         unless is_list(value) and Enum.all?(value, &is_atom(&1)) do
-          Mix.raise "Application extra applications (:extra_applications) should be a list of atoms, got: #{inspect value}"
+          Mix.raise(
+            "Application extra applications (:extra_applications) should be a list of atoms, got: " <>
+              inspect(value)
+          )
         end
+
       {:applications, value} ->
         unless is_list(value) and Enum.all?(value, &is_atom(&1)) do
-          Mix.raise "Application applications (:applications) should be a list of atoms, got: #{inspect value}"
+          Mix.raise(
+            "Application applications (:applications) should be a list of atoms, got: " <>
+              inspect(value)
+          )
         end
+
       {:env, value} ->
         unless Keyword.keyword?(value) do
-          Mix.raise "Application environment (:env) should be a keyword list, got: #{inspect value}"
+          Mix.raise(
+            "Application environment (:env) should be a keyword list, got: #{inspect(value)}"
+          )
         end
+
       {:start_phases, value} ->
         unless Keyword.keyword?(value) do
-          Mix.raise "Application start phases (:start_phases) should be a keyword list, got: #{inspect value}"
+          Mix.raise(
+            "Application start phases (:start_phases) should be a keyword list, got: " <>
+              inspect(value)
+          )
         end
+
       {:mod, []} ->
         :ok
+
       {:mod, {module, _args}} when is_atom(module) ->
         :ok
+
       {:mod, value} ->
-        Mix.raise "Application callback module (:mod) should be either [] or {module, start_args}, got: #{inspect value}"
+        Mix.raise(
+          "Application callback module (:mod) should be either [] or {module, start_args}, got: " <>
+            inspect(value)
+        )
+
       _ ->
         :ok
-    end
+    end)
 
     properties
   end
@@ -260,12 +312,11 @@ defmodule Mix.Tasks.Compile.App do
   defp apps_from_prod_non_optional_deps(properties) do
     included_applications = Keyword.get(properties, :included_applications, [])
 
-    for %{app: app, opts: opts, top_level: true} <- Mix.Dep.cached,
+    for %{app: app, opts: opts, top_level: true} <- Mix.Dep.cached(),
         Keyword.get(opts, :app, true),
         Keyword.get(opts, :runtime, true),
         not Keyword.get(opts, :optional, false),
-        app not in included_applications,
-        do: app
+        app not in included_applications, do: app
   end
 
   defp normalize_apps(apps, properties, config) do