update-npm-deps.nix

  updateNpmDeps = pkgs.writeScriptBin "update-frontend-deps" ''
    #!${pkgs.stdenv.shell}
    set -e
    echo; echo "Pinning node dependencies from ./package.json ..."; echo
    ${pkgs.nix}/bin/nix-instantiate --strict --json --eval --expr '
      (import <nixpkgs> {}).lib.mapAttrsToList
        (name : value : { "${"\${name}"}" = value; })
        (builtins.fromJSON (builtins.readFile ./package.json)).dependencies
    ' > node-modules.json
    ${pkgs.nodePackages.node2nix}/bin/node2nix \
      --composition node-modules.nix \
      --input node-modules.json \
      --output node-modules-generated.nix \
      --node-env node-env.nix \
      --flatten \
      --pkg-name nodejs-6_x
    ${pkgs.gnused}/bin/sed -i -e "s| sources.\"elm-0.18| #sources.\"elm-0.18|" node-modules-generated.nix
    ${pkgs.gnused}/bin/sed -i -e "s| name = \"elm-webpack-loader\";| dontNpmInstall = true; name = \"elm-webpack-loader\";|" node-modules-generated.nix
    ${pkgs.gnused}/bin/sed -i -e "s| name = \"elm-test\";| dontNpmInstall = true; name = \"elm-test\";|" node-modules-generated.nix
  ''