[Haskell-beginners] a simple little problem

Can someone suggest an elegant way to write the following? fn :: [Maybe Float] -> Maybe Float in which, if the input list has all Nothing, then the result is Nothing if the input list has one or more Just x, then the result is Just x (in which the x is picked arbitrarily, could be the first one or last one) I have something like import Data.Maybe fn list = case catMaybes list of [] -> Nothing [x:_] -> fromJust x Next, an augmentation of this idea (or similar idea). fn2 :: [Maybe Float] -> Map Int Float When a Just x appears at position n in the list, then put (key=n, value=x) into the map. I have: import qualified Data.Map as M f2 list = M.fromList [(n,x) | (n,Just x) <- zip [0..] list]