[Haskell-cafe] Constructing a datatype given just its constructor as a string?

Trying to create a datatype/constructor given just its constructor as a string, something like: mkConstr :: String -> Constr parseData :: (Data a) => String -> a ***without knowing in advance anything about the datatype apart from the string contents*** So, not something like: parseData "Just 3" :: [Maybe] but simply: parseData "Just 3" (This is linked to the other post: the goal is to be able to deserialize xml without needing to know in advance the data type we are deserializing)