Almost got nix-build working

for now we can just deploy via: nix-shell --command "yarn prod"

default.nix

@@ -2,13 +2,54 @@
 }:
 
 let
+  package = builtins.fromJSON (builtins.readFile ./package.json);
+  yarn2nix = import (pkgs.fetchFromGitHub {
+    owner = "moretea";
+    repo = "yarn2nix";
+    rev = "9e7279edde2a4e0f5ec04c53f5cd64440a27a1ae";
+    sha256 = "sha256-x77mYSvwA4bd/uCwL0rRw+8mwH+dR/UfWnn4YXmm4n8=";
+  }) { inherit pkgs; };
+  yarnPkg = yarn2nix.mkYarnPackage rec {
+    name = "${package.name}-yarn-${package.version}";
+    src = null;
+    dontUnpack = true;
+    packageJSON = ./package.json;
+    yarnLock = ./yarn.lock;
+    preConfigure = ''
+      mkdir ${package.name}
+      cd ${package.name}
+      ln -s ${packageJSON} ./package.json
+      ln -s ${yarnLock} ./yarn.lock
+    '';
+    yarnPreBuild = ''
+      mkdir -p $HOME/.node-gyp/${pkgs.nodejs.version}
+      echo 9 > $HOME/.node-gyp/${pkgs.nodejs.version}/installVersion
+      ln -sfv ${pkgs.nodejs}/include $HOME/.node-gyp/${pkgs.nodejs.version}
+    '';
+    pkgConfig = {
+      node-sass = {
+        buildInputs = [ pkgs.python pkgs.libsass pkgs.pkgconfig];
+        postInstall = ''
+          LIBSASS_EXT=auto yarn --offline run build
+          rm build/config.gypi
+        '';
+      };
+    };
+    publishBinsFor =
+      [ "webpack"
+        "webpack-dev-server"
+      ];
+  };
 in pkgs.stdenv.mkDerivation {
-  name = "nixos-search";
+  name = "${package.name}-${package.version}";
   src = pkgs.lib.cleanSource ./.;
 
   buildInputs =
+    [ yarnPkg
+    ] ++
     (with pkgs; [
       nodejs
+      elm2nix
     ]) ++
     (with pkgs.nodePackages; [
       yarn
@@ -18,8 +59,36 @@ in pkgs.stdenv.mkDerivation {
       elm-format
     ]);
 
+  # TODO: elm-webpack-loader is trying to download the packages instead of using 
+  # configurePhase = pkgs.elmPackages.fetchElmDeps {
+  #   elmPackages = import ./elm-srcs.nix;
+  #   elmVersion = pkgs.elmPackages.elm.version;
+  #   registryDat = ./registry.dat;
+  # };
+
+  patchPhase = ''
+    rm -rf elm-stuff
+    rm -rf node_modules
+    ln -sf ${yarnPkg}/libexec/${package.name}/node_modules .
+  '';
+
+  buildPhase = ''
+    # Yarn writes cache directories etc to $HOME.
+    export HOME=$PWD/yarn_home
+    yarn prod
+  '';
+
+  installPhase = ''
+    mkdir -p $out
+    cp -R ./dist/* $out/
+  '';
   shellHook = ''
+    rm -rf node_modules
+    ln -sf ${yarnPkg}/libexec/${package.name}/node_modules .
     export PATH=$PWD/node_modules/.bin:$PATH
+    echo "============================"
+    echo "= To develop run: yarn dev ="
+    echo "============================"
   '';
 
 }