ft :: Floating n
     => n              -- ^ Degree of turn
     -> TurtleState n  -- ^ Turtle to turn
     -> TurtleState n  -- ^ Resulting turtle
left d = turnTurtle (^+^ (d @@ deg))


left :: Floating n
     => n              -- ^ Degree of turn
     -> TurtleState n  -- ^ Turtle to turn
     -> TurtleState n
left d = turnTurtle (^+^ (d @@ deg))
left d = turnTurtle (^+^ (d @@ deg))