Here's how I would do it:
Write two functions. One (f) takes the int and gets the IO record. One
(g) takes a (non-IO) record and returns the string. Now you can use a bind
(=<<) to combine the two.
Once you've got that working, you can move the bits into the where clause
of your original function.
Hope this helps.
J
On Thursday, January 15, 2015, Miro Karpis
Hi,
please is there a way to have guards with 'where' that communicates with IO? Or is there some other more elegant way? I can do this with classic if/else,...but I just find it nicer with guards.
I have something like this (just an example):
f :: Int -> IO String f x | null dbOutput = return "no db record" | otherwise = return "we got some db records" where dbOutput = getDBRecord x
getDBRecord :: Int -> IO [Int] getDBRecord recordId = do putStrLn $ "checking dbRecord" ++ show recordId --getting data from DB return [1,2]
problem is that db dbOutput is IO and the guard check does not like it:
Couldn't match expected type ‘[a0]’ with actual type ‘IO [Int]’ In the first argument of ‘null’, namely ‘dbOutput’ In the expression: null dbOutput
Cheers, Miro
-- Sent from an iPhone, please excuse brevity and typos.