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.

On Thursday, January 15, 2015, Miro Karpis <miroslav.karpis@gmail.com> wrote:

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