never executed always true always false

    1 module HelVM.HelMA.Automata.Piet.Types.Brightness (
    2   brightnessChange,
    3   Brightness(..),
    4 ) where
    5 
    6 import           HelVM.HelMA.Automata.Piet.Types.Extra
    7 
    8 brightnessChange :: Brightness -> Brightness -> Brightness
    9 brightnessChange = changeDiff 3
   10 
   11 data Brightness = Light | Normal | Dark
   12   deriving stock (Bounded , Show , Read, Eq , Ord , Enum)