On Mon, May 18, 2009 at 3:08 AM, Neil Brown
With ErrorT you can use throwError when you want to break out of the block and give back an error, which seems to fit what you were doing.
Of course, now that you are using throwError, you can remove a lot of the extra indentation:
insertNote :: NoteRecord -> Connection -> IO () insertNote nr conn = either putStrLn return =<< runErrorT (do -- Check if it exists in the database already. status <- liftIO $ checkPreExistingText nr conn when status $ throwError "Skipping... text exists already." -- Find best fit for all topics and source. -- See type signatures below. bestFitTopics <- liftIO $ fitTopics nr conn bestFitSource <- liftIO $ fitSource nr conn when (any isNothing bestFitTopics) $ throwError "Error... some topic couldn't be matched." when (isNothing bestFitSource) $ throwError "Error.. source couldn't be matched." b <- liftIO $ isUserOkay nr bestFitTopics bestFitSource when (not b) $ throwError "Abort due to user request." -- Create a new NoteRecord with matched -- and validated topics/source. let nrValidated = nr { recordTopics = bestFitTopics, recordSource = bestFitSource } liftIO $ insertRow nrValidated conn )
-- ryan