new package watch-outputs and example of its use

pkgs/watch-outputs/default.nix

@@ -0,0 +1,35 @@
+{
+  fetchurl,
+  writeFennel,
+  fennel,
+  runCommand,
+  lua,
+  anoia,
+  linotify,
+  lualinux,
+  stdenv
+}:
+let name = "watch-outputs";
+in stdenv.mkDerivation {
+  inherit name;
+  src = ./.;
+
+  buildInputs = [lua];
+#  doCheck = true;
+
+  buildPhase = ''
+    cp -p ${writeFennel name {
+      packages = [
+        anoia
+        lualinux
+        linotify
+        fennel
+      ] ;
+      mainFunction = "run";
+    } ./watch-outputs.fnl } ${name}
+  '';
+#  checkPhase = "make check";
+  installPhase = ''
+    install -D ${name} $out/bin/${name}
+  '';
+}