CODEWITHSUNDEEP
listhaskelltuples
Computer Geek
Computer Geek

Reputation: 105

Adding corresponding values of Tuple in a list in Haskell

I have a list for example: [(1,2),(3,4),(5,6)] and the function should return me the sum of the corresponding Tuples. So, this list should return (9,12). I know how to make the tuples add up individually but I have having troubles doing it them together. 

sumSecondTuple list = foldl (\acc (x,y) -> (+) y acc) 0 list  
    sumFirstTuple list = foldl (\acc (x,y) -> (+) x acc) 0 list

I have this much so far. Is there a way I can incooperate them together?

Upvotes: 2

Views: 275

Answers (1)

Daniel R. Torres Ruiz
Daniel R. Torres Ruiz

Reputation: 130

You can also use foldr1:

foldr1 :: Foldable t => (a -> a -> a) -> t a -> a

In this case,

sumSecondTuple :: Num a => [(a,a)] -> (a,a)
sumSecondTuple = foldr1 f
    where
        f = (\ (a,b) (c,d) -> (a+c,b+d) )

However, sumSecondTuple [] returns an exception Prelude.foldr1: empty list. So, it's better to use foldr than use foldr1 on this occasion.

Upvotes: 1

Related Questions