"Object Oriented Programming" in Haskell

AlmostOOP.hs

class Monad m => NotificationQueue m where
  readNotifications :: m [Message]
  ackNotification   :: Message -> m ()

class Repository m where
  readRules     :: S3Location -> m (Maybe [Rule])
  writePolicies :: S3Location -> [Policy] -> m (Maybe ETag)


readSubmissions :: ( NotificationQueue m
                   , Repository m
                   , Logging m) => m ()
readSubmissions = do
  msgs <- readNotifications
  logInfo ("Received messages: " ++ show (length msgs))
  forM_ msgs $ \msg -> do
    rules <- readRules (locationFromMessage msg)
    error "Implement me"