haskell-hindent: byte-compile installed elisp code

pkgs/development/haskell-modules/configuration-common.nix

@@ -969,4 +969,21 @@ self: super: {
     '';
   });
 
+  # Byte-compile elisp code for Emacs.
+  hindent = overrideCabal super.hindent (drv: {
+    executableToolDepends = drv.executableToolDepends or [] ++ [pkgs.emacs];
+    postInstall = ''
+      local lispdir=( "$out/share/"*"-${self.ghc.name}/${drv.pname}-${drv.version}/elisp" )
+      pushd >/dev/null $lispdir
+      for i in *.el; do
+        emacs -Q -L . -L ${pkgs.emacs24Packages.haskellMode}/share/emacs/site-lisp \
+          --batch --eval "(byte-compile-disable-warning 'cl-functions)" \
+          -f batch-byte-compile $i
+      done
+      popd >/dev/null
+      mkdir -p $out/share/emacs
+      ln -s $lispdir $out/share/emacs/site-lisp
+    '';
+  });
+
 }