On Wed, 23 Oct 2013 23:11:32 +0200, Miro Karpis wrote:

Please, can you help me with following?... I have a working code but am not very happy with the error handling in "updateStocks" function. It does what it should, but I would like to implement some kind of guards. Problem is that it always ends it some error + am not sure if I can use guards in inside defined variable. Pls. what would you suggest?

httpExceptionHandler :: HttpException -> IO L.ByteString httpExceptionHandler e = (putStrLn "Error: simpleHttp returned exception") >> (return L.empty)

getStocks :: String -> IO L.ByteString getStocks url = (simpleHttp url) `X.catch` httpExceptionHandler

updateStocks :: IO String updateStocks = do yqlResult <- getStocks testQuery case yqlResult of x | x == L.empty -> return "return exception" | otherwise -> return "here I will call another function"

I think you need to give more details to say anything about this. What is the indication that there is nothing more to download? I have some suggestions for code improvement: - you use more parentheses than necessary, download hlint from hackage, it can suggest improvements - the code:

case yqlResult of x | x == L.empty -> return "return exception" | otherwise -> return "here I will call another function"

can be simplified to:

if yqlResult == L.empty then return "return exception" else return "here I will call another function"

or even:

return if yqlResult == L.empty then "return exception" else "here I will call another function"

Regards, Henk-Jan van Tuyl -- Folding@home What if you could share your unused computer power to help find a cure? In just 5 minutes you can join the world's biggest networked computer and get us closer sooner. Watch the video. http://folding.stanford.edu/ http://Van.Tuyl.eu/ http://members.chello.nl/hjgtuyl/tourdemonad.html Haskell programming --