>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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