Re: [Haskell-cafe] Cost: (:) vs head

michael rice schrieb:

Which of these would be more costly for a long list?

f :: [Int] -> [Int] f [x] = [x] f (x:xs) = x + (head xs) : f xs

f :: [Int] -> [Int] f [x] = [x] f (x:y:xs) = x + y : f (y:xs)

What about empty lists? How about zipWith (+) xs (drop 1 xs ++ [0]) ? Since I often need to combine adjacent list elements, I have defined mapAdjacent in utility-ht.