src/Cardinal.hs

   1 module Cardinal
   2 where
   3
   4 data Cardinal = F
   5               | B
   6               | L
   7               | R
   8               | T
   9               | D
  10               | Sum Cardinal Cardinal
  11               | Difference Cardinal Cardinal
  12               | Product Cardinal Cardinal
  13               | ScalarProduct Double Cardinal
  14                 deriving (Show, Eq)
  15
  16 instance Num Cardinal where
  17     x + y = Sum x y
  18     x - y = Difference x y
  19     x * y = Sum x y
  20     negate x = ScalarProduct (-1) x
  21     abs x = x
  22     signum x = x
  23     fromInteger _ = F -- Whatever.