prop_binary :: (a -> a -> a) -> W a -> W a -> Bool
prop_binary op wrappedm@(W m) wrappedn@(W n) =
  m `op` n == result
  where (W result) = wrappedm `op` wrappedn

{-# LANGUAGE AllowAmbiguousTypes, FlexibleContexts, Rank2Types - #}
prop_binary :: (Eq b, Num b, Num (W b)) => (forall a. (Num a) => a -> a -> a) -> W a -> W a -> Bool
(...)