CODEWITHSUNDEEP
haskellfunctional-programming
Alice
Alice

Reputation: 79

partialSum in haskell

I need to compute the partial sums of a list in haskell. Any ideas of how can I do that?

if I have

partialSum (1:3:5:[]) => (1:4:9:[])
partialSum [] => []
partialSum (from 1) => 1:3:6:10:...

Upvotes: 1

Views: 896

Answers (1)

obadz
obadz

Reputation: 909

partialSum :: Num a => [a] -> [a]
partialSum = drop 1 . scanl (+) 0

λ> take 10 $ partialSum [1..]
[1,3,6,10,15,21,28,36,45,55]

EDIT: OP requested a version without scanl:

partialSum :: Num a => [a] -> [a]
partialSum (x:xs) = x : map (+ x) (partialSum xs)
partialSum []     = []

Upvotes: 7

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