I have a following function:

f1 :: (String, String) -> IO (Maybe String)

which I would like to apply to a list of tuples.I have defined the function like this, but that gives me error (below):

f2 :: [(String, String)] -> IO (Maybe String)

f2 x = foldM f1 0 x 

error:

Couldn't match expected type `IO (Maybe String)'  with actual type `[b0] -> m0 (String, String)' In the return type of a call of `foldM'

thanks,

m.