Haskell data type in list

I have a data type which looks like this:

data Vector3 = V Int Int Int deriving (Eq, Show)

And I have to write this function:

vectorListSum :: [Vector3] -> Vector3

Which should sum the parameters on the same index, so:

(V1 a1 b1 c1) + (V2 a2 b2 c2) => (V3 a1+a2 b1+b2 c1+c2)

And so on, depending on how many elements the list have

I tried something like this:

vectorListSum :: [Vector3] -> Vector3
vectorListSum [] = V 0 0 0
vectorListSum ((V a b c):xs) = ...

But I couldn’t go any further

>Solution :

You can work with foldr or foldl:

vectorListSum :: [Vector3] -> Vector3
vectorListSum = foldr f (V 0 0 0)
    where f (V …) (V …) = …

where f takes as input a vector and the "fold" of the rest of the list, and thus determines the fold of the entire list. I leave filling in the … parts as an exercise.