newtype TypeMap = TypeMap (Map.Map TypeRep Dynamic)
lookup :: Typeable a => TypeMap -> Maybe a
lookup (TypeMap mp) = res
where res = liftM (fromJust . fromDynamic) $ Map.lookup (typeOf $
fromJust res) mp
It seems that the `res` in `fromJust res` has not been defined ?
Sincerely!
-----
fac n = let { f = foldr (*) 1 [1..n] } in f
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