import "Prelude" hiding (findFirst)

findFirst :: (a -> <e> Maybe b) -> [a] -> Maybe b
findFirst f l = loop 0
  where
    len = length l
    loop i                         
        | i >= len  = Nothing
        | otherwise = match f (l!i) with
                        s @ (Just _) -> s
                        Nothing      -> loop (i+1)

main = "Not to be executed"
--
9:29-9:36: Side-effect a is forbidden here.