[Haskell] [newbye] 'Just a'

Hi all. I'm experimenting with haskell and its type system. I've done a function which scans a list, and returns "Just a" value if the element is found, or Nothing. get :: a -> Maybe a and implemented getAorB :: Maybe a -> Maybe a -> a getAorB a b = ... a function which returns "Just (get a)" or "Just (get b)" if (get a) is Nothing (excluding failures in both). By now, I've implemented it in terms of pattern matching: getAorB a b = f (get a) (get b) where f (Just a) Nothing = a f Nothing (Just a) = a but I'd like to know if there are other possible ways to do it, possibly without enforcing an evaluation order like pattern matching does.