Attempt 2 at reddit challenge 115

sumPair2.hs

sumPair :: [Int] -> Int -> [(Int,Int)]
sumPair xs num = helper xs num []
    where helper [] _ [] = []
          helper [] _ [z] = []
          helper [] num (z:zs) = helper (z:zs) num []
          helper (x:[]) _ [] = []
          helper (x:[]) num zs = helper zs num []
          helper (x:y:xs) num []
              | x + y == num = (min x y,max x y):(helper xs num []) 
              | otherwise = helper (x:xs) num [y]
          helper (x:y:xs) num [z] 
              | x + y == num = (min x y,max x y):(helper (z:xs) num []) 
              | otherwise = helper (x:xs) num (y:[z])
          helper (x:y:xs) num (z:zs) 
              | x + y == num = (min x y,max x y):(helper ((z:zs) ++ xs) num []) 
              | otherwise = helper (x:xs) num (y:z:zs)