never executed always true always false

    1 module HelVM.HelMA.Automata.Piet.Types.DirectionPointer (
    2   addCoordinates,
    3   rotate,
    4   DirectionPointer(..),
    5 ) where
    6 
    7 import           HelVM.HelMA.Automata.Piet.Types.Coordinates
    8 import           HelVM.HelMA.Automata.Piet.Types.Extra
    9 
   10 addCoordinates :: DirectionPointer -> Coordinates -> Coordinates
   11 addCoordinates DPRight (x, y) = (x + 1, y)
   12 addCoordinates DPDown  (x, y) = (x, y + 1)
   13 addCoordinates DPLeft  (x, y) = (x - 1, y)
   14 addCoordinates DPUp    (x, y) = (x, y - 1)
   15 
   16 rotate :: Int -> DirectionPointer -> DirectionPointer
   17 rotate = change 4
   18 
   19 data DirectionPointer = DPRight | DPDown | DPLeft | DPUp
   20   deriving stock (Show, Read, Eq, Ord, Enum, Bounded)