Productionize habit-screens

At some point I should document or write a script for how I package Elm projects
with Nix to be deployed on my website. For now, I'm modeling everything after my
previous success LearnPianoChords.

website/default.nix

@@ -8,6 +8,6 @@ pkgs.stdenv.mkDerivation {
     cp $src/index.html $out
 
     mkdir -p $out/habits
-    cp ${briefcase.website.habits} $out/habits/index.html
+    cp ${briefcase.website.habit-screens} $out/habits/index.html
   '';
 }

website/habit-screens/default.nix

@@ -1,8 +1,6 @@
-{ nixpkgs ? <nixpkgs>
-, config ? {}
-}:
+{ pkgs ? <nixpkgs> , ... }:
 
-with (import nixpkgs config);
+with pkgs;
 
 let
   mkDerivation =
@@ -42,12 +40,22 @@ let
         '') targets)}
       '';
     };
-in mkDerivation {
+  mainDotElm = mkDerivation {
     name = "elm-app-0.1.0";
     srcs = ./elm-srcs.nix;
     src = ./.;
     targets = ["Main"];
     srcdir = "./src";
-  outputJavaScript = false;
+    outputJavaScript = true;
+  };
+in stdenv.mkDerivation {
+  name = "habit-screens";
+  buildInputs = [];
+  src = builtins.path { path = ./.; name = "habit-screens"; };
+  buildPhase = ''
+    mkdir -p $out
+    cp index.html output.css ${mainDotElm}/Main.min.js $out
+  '';
+  dontInstall = true;
 }