-- | display a single value  
dispRange :: Disp a => a -> a -> String
dispRange x y = sdisp x  ++ " - " ++ sdisp y
dispRange :: Disp a => a -> a -> String
dispRange x y = sdisp x  ++ " - " ++ sdisp y
dispRange x y = sdisp x  ++ " - " ++ sdisp y