newtype EventId =
  EventId
    { getEventId :: ByteString
    }
  deriving (Eq)

instance Show EventId where
    showsPrec _ = shows . B16.encodeBase16 . getEventId

instance ToJSON EventId where
    toJSON e = AesonTypes.String $ pack $ exportEventId e

instance FromJSON EventId where
    parseJSON = withObject "EventId" $ \i -> do
        i' <- i .: "id"
        return $ fromJust $ eventId' i'

####

• No instance for (FromJSON ByteString) arising from a use of ‘.:’
    • In a stmt of a 'do' block: i' <- i .: "id"
      In the expression:
        do i' <- i .: "id"
           return $ fromJust $ eventId' i'
      In the second argument of ‘($)’, namely
        ‘\ i
           -> do i' <- i .: "id"
                 return $ fromJust $ eventId' i'’
   |
52 |         i' <- i .: "id"
   |               ^^^^^^^^^