> instance (Ord a, Bits a, Bounded a, Integral a, LargeWord a, > Bits b, Bounded b, Integral b, LargeWord b) => > Bounded (LargeKey a b) where > minBound = 0 > maxBound = > fromIntegral $ > (1 + fromIntegral (maxBound::b))* > (1 + fromIntegral (maxBound::a)) - 1 > > Hugs rejects it with +N -98 with
One fix is to bring type variables into the local scope, for example, > instance (Ord a, Bits a, Bounded a, Integral a, LargeWord a, > Bits b, Bounded b, Integral b, LargeWord b) => > Bounded (LargeKey a b) where > minBound = 0 > maxBound :: (LargeKey a b) = > fromIntegral $ > (1 + fromIntegral (maxBound::b))* > (1 + fromIntegral (maxBound::a)) - 1 You still need -98 flag for Hugs. Another solution is totally Haskell98: introduce two functions > aoflk:: (LargeKey a b) -> a; aoflk = undefined > boflk:: (LargeKey a b) -> b; boflk = undefined then maxBound can be implemented as > maxBound = result where > result = > fromIntegral $ > (1 + fromIntegral (maxBound `asTypeOf` (boflk result)))* > (1 + fromIntegral (maxBound `asTypeOf` (aoflk result))) - 1 The apparent recursion in the above definition is superficial. The definition isn't actually recursive. We merely need the type of the 'result' rather than its value. _______________________________________________ Haskell mailing list [EMAIL PROTECTED] http://www.haskell.org/mailman/listinfo/haskell
