instance ToJSON Day where
    toJSON = toJSON . show

instance FromJSON Day where
    parseJSON x = do
        s <- parseJSON x
        case reads s of
            (d, _):_ -> return d
            [] -> mzero 

instance ToJSON TimeOfDay where
    toJSON = toJSON . show

instance FromJSON TimeOfDay where
    parseJSON x = do
        s <- parseJSON x
        case reads s of
            (d, _):_ -> return d
            [] -> mzero

instance ToJSON Checkmark where
    toJSON Active   = A.String "Active"
    toJSON Inactive = A.String "Inactive"            

instance FromJSON Checkmark where
    parseJSON (A.String "Active") = return Active
    parseJSON (A.String "Inactive") = return Inactive    
    parseJSON _ = mzero