xmonad.hs

import System.Posix.Env (getEnv)
import Data.Maybe (maybe)

import XMonad
import XMonad.Config.Desktop
import XMonad.Config.Gnome
import XMonad.Config.Kde
import XMonad.Config.Mate
import XMonad.Config.Xfce

main = do
     session <- getEnv "DESKTOP_SESSION"
     xmonad  $ ( maybe desktopConfig desktop session )
         { modMask = mod4Mask }

desktop "gnome" = gnomeConfig
desktop "kde" = kde4Config
desktop "xfce" = xfceConfig
desktop "xmonad-mate" = mateConfig
desktop _ = desktopConfig