Let's be consistent about code reuse

mix.exs

@@ -1,16 +1,29 @@
 defmodule Lytedev.MixProject do
   use Mix.Project
 
+  @src_path "src"
+  @config_path Path.join(@src_path, "config.exs")
+  @test_path Path.join(@src_path, "test")
   @build_path "build"
   @deps_path Path.join(@build_path, "deps")
+  @docs_path Path.join(@build_path, "docs")
+
+  def deps, do: [
+    {:ex_doc, "~> 0.23.0", only: :dev},
+    {:jason, "~> 1.0"},
+    {:finch, "~> 0.5"},
+    {:elli, "~> 3.0"},
+  ]
+
+  def docs, do: [output: @docs_path]
 
   def project(), do: [
     app: :lytedev,
     version: "0.1.0",
     elixir: "~> 1.7",
-    elixirc_paths: ["src"],
-    config_path: "src/config.exs",
-    test_paths: ["src/test"],
+    elixirc_paths: [@src_path],
+    config_path: @config_path,
+    test_paths: [@test_path],
     start_permanent: true,
     build_path: @build_path,
     deps_path: @deps_path,
@@ -22,15 +35,4 @@ defmodule Lytedev.MixProject do
     mod: {Lytedev.Application, []},
     extra_applications: [:logger],
   ]
-
-  def deps, do: [
-    {:ex_doc, "~> 0.23.0", only: :dev},
-    {:jason, "~> 1.0"},
-    {:finch, "~> 0.5"},
-    {:elli, "~> 3.0"},
-  ]
-
-  def docs, do: [
-    output: "build/docs",
-  ]
 end