Hide the NSP workspace in xmobar while it's empty

.config/xmonad/xmonad.hs

@@ -3,6 +3,7 @@
 import Data.Monoid
 import Graphics.X11.ExtraTypes.XF86
 import Control.Monad (forM_, liftM2, when)
+import Data.Maybe (isJust)
 import XMonad
 import XMonad.Actions.OnScreen (greedyViewOnScreen)
 import XMonad.Actions.PhysicalScreens
@@ -241,6 +242,8 @@ myXmobarPP =
       ppHidden = cultured . wrap " " "",
       ppHiddenNoWindows = outerspace . wrap " " "",
       ppUrgent = sunsetorange . wrap (keylime "!") (keylime "!"),
+      -- NamedScratchpad never removes NSP once created; hide it while it's empty
+      ppSort = (. filter (\w -> W.tag w /= scratchpadWorkspaceTag || isJust (W.stack w))) <$> ppSort def,
       ppOrder = \[ws, l, _, wins] -> [ws, l, wins],
       ppExtras = [logTitles formatFocused formatUnfocused]
     }