Each element is the sum of itself with the next element of a List: now do this point-free in Haskell

Question

Here it is the best I can do (I am a noob using Haskell):

map (\(y, z) -> y + z) (zip x (tail x))

I'm looking for a point-free solution.

Answer 1

Pointfree, eh? Let's ask lambdabot.

<DanBurton> @pl map (\(y, z) -> y + z) (zip x (tail x))
<lambdabot> zipWith (+) x (tail x)

Assuming that x is simply the input to this "function"

<DanBurton> @pl \x -> map (\(y, z) -> y + z) (zip x (tail x))
<lambdabot> map (uncurry (+)) . ap zip tail

Personally I'd go with the former; I'm not a fan of Lambdabot's gratuitous use of uncurry and ap.

Answer 2

You could use &&& from Control.Arrow (along with the zipWith trick from Dan's solution):

foo = uncurry (zipWith (+)) . (tail &&& id)