gistfile1.hs

data Logic a where
    I :: Int  -> Logic Int 
    B :: Bool -> Logic Bool

lEqual :: Logic a -> Logic b -> Bool
lEqual (I x) (I y)     = x == y
lEqual (B x) (B y)     = x ==  y
lEqual _ _             = False

instance Eq (Logic a) where 
  (==)  =  lEqual