exactlyFour :: String -> String
exactlyFour s =
    pad (4-len) $ drop (len-4) s
  where
    len = length s
    pad 0 cs = cs
    pad n cs = '0' : pad (n-1) cs


-- | Default separator; comma followed by space, if spaces are enabled.
exactlyFour :: String -> String
exactlyFour s =
    pad (4-len) $ drop (len-4) s
  where
    len = length s
    pad 0 cs = cs
    pad n cs = '0' : pad (n-1) cs


-- | Default separator; comma followed by space, if spaces are enabled.
exactlyFour s =
    pad (4-len) $ drop (len-4) s
  where
    len = length s
    pad 0 cs = cs
    pad n cs = '0' : pad (n-1) cs


-- | Default separator; comma followed by space, if spaces are enabled.