{-11.1.1-}

addPos :: [a] -> [(Int,a)]
addPos xs = undefined

{-11.1.2-}

prodSumEven :: [Int] -> Int
prodSumEven xs = undefined

{-11.1.3-}

prodSum :: (Int -> Bool) -> [Int] -> Int
prodSum cond_f xs  = undefined


{- 11.2 -}

{- 11.2.2 -}
filterr :: (a -> Bool) -> [a] -> [a]
filterr f xs = undefined

filterl :: (a -> Bool) -> [a] -> [a]
filterl f xs = undefined

{- 11.2.3 -}
findFirst :: (a -> Bool) -> [a] -> Maybe a
findFirst f xs = undefined

findLast :: (a -> Bool) -> [a] -> Maybe a
findLast f xs = undefined