úÎ S None!"Since  is a GADT, our A function needs a type class in order to be implemented. Which B gets used is chosen in compile-time. As a bonus, we implement  in the same way.From  fb-persistent . Since 0.3.From  fb-persistentA. Since 0.1.3. Note that your fields should either be of type  or , not a polymorphic  kind. Expiration time of s( is saved with precision of one second. From  fb-persistent . Since 0.3. From  fb-persistent. Since 0.1.2.We use  ByteStringB for historical purposes in order to maintain compatibility with  fb < 0.13. From  fb-persistent . Since 0.3. From  fb-persistent . Since 0.1.         fb-persistent-0.3.4Facebook.PersistentAccessTokenKindfb-1.0.6Facebook.Types AccessTokencereal-0.4.1.0Data.SerializegetaccessTokenGetput$fPersistFieldSqlAccessToken$fPersistFieldAccessTokenUserAccessTokenAppAccessToken$fPersistFieldSqlId$fPersistFieldId$fPersistFieldSqlAction$fPersistFieldActionaccessTokenPutgetTextputTextgetIdputId putUTCTime getUTCTimeaccessTokenUnknownVersion$fAccessTokenKindAppKind$fAccessTokenKindUserKind