Forget it. It's more clear reading further. Sorry for the noise.
On Sat, Dec 27, 2008 at 1:02 AM, Oscar Picasso <oscarpica...@gmail.com>wrote: > From Real World Haskell: > > data JValue = JString String > | JNumber Double > | JBool Bool > | JNull > | JObject [(String, JValue)] > | JArray [JValue] > deriving (Eq, Ord, Show) > > .... > type JSONError = String > > class JSON a where > toJValue :: a -> JValue > fromJValue :: JValue -> Either JSONError a > > instance JSON JValue where > toJValue = id -- Really ? > fromJValue = Right > > Now, instead of applying a constructor like JNumber to a value to wrap it, >> we apply the toJValue function. If we change a value's type, the compiler >> will choose a suitable implementation of toJValue to use with it. > > > Actually it does not work. And I don't see how it could with this toJValue > implementation. Is it possible to make it work by providing another > implementation? > > Oscar >
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