myXmobarPP :: PP
myXmobarPP =
  def
    { ppSep = white " • ",
      ppTitleSanitize = xmobarStrip,
      ppCurrent = invert3D lightGreen darkGreen medGreen 2,
      ppHidden = djungle3D . white . xmobarBorder "Top" "#FFF" 1,
      ppVisible = myPPVisible,
      ppHiddenNoWindows = myPPNoWindows,
      ppVisibleNoWindows = Just (const $ myPPNoWindows switcheroo),
      ppUrgent = red . wrap (yellow "!") (yellow "!"),
      ppOrder = \[ws, l, _, wins] -> [ws, l, wins],
      ppExtras = [logTitles formatFocused formatUnfocused],
      ppWsSep = "",
      ppPrinters = isEmptyCurrent ?-> ppIsEmptyCurrent -- If I exhange the second argument (ppIs..) to e.g. "ppCurrent", it works but in this case the function is apparently missing a parameter "PP".
    }
  where
    ppIsEmptyCurrent :: WorkspaceId -> String
    ppIsEmptyCurrent = invert3D lightGreen darkGreen medGreen 2 . lowWhite
    cond ?-> ppr = (asks cond >>= guard) *> asks (ppr . wsPP)

    djungle3D = create3D lightGreen darkGreen medGreen 2
    myPPVisible = const $ djungle3D switcheroo
    myPPNoWindows = djungle3D . lowWhite
    formatFocused = wrap (white "[") (white "]") . magenta . ppWindow
    formatUnfocused = wrap (lowWhite "[") (lowWhite "]") . blue . ppWindow
    create3D lc dc mc w = xmobarBorder "Right" dc w . xmobarBorder "Bottom" dc (w -1) . xmobarBorder "Top" lc w . xmobarBorder "Left" lc w . xmobarColor "white" mc . (' ' :) . (++ " ")
    invert3D lc dc = create3D dc lc
    switcheroo = "<fn=1>\61561</fn>"

    ppWindow :: String -> String
    ppWindow = xmobarRaw . (\w -> if null w then "untitled" else w) . shorten 30

    -- colors
    blue, lowWhite, magenta, red, white, yellow :: String -> String
    magenta = xmobarColor "#ff79c6" ""
    blue = xmobarColor "#bd93f9" ""
    white = xmobarColor "#f8f8f2" ""
    yellow = xmobarColor "#f1fa8c" ""
    red = xmobarColor "#ff5555" ""
    lowWhite = xmobarColor "#bbbbbb" ""
    darkGreen = "#0c231e" -- "#2e4941"
    lightGreen = "#597268" -- "#a7b6a3"
    medGreen = "#2e4941" -- "#597268"

isEmptyCurrent :: WS -> Bool
isEmptyCurrent WS {..} = isNothing $ W.peek wsWindowSet