Question

I cant seem to find any information on a high order function that would do this. I found a reference to cadd a few places but could not find any information in a haskell api.

I just simply want to take a list of floats, and create another list from it by cumulatively adding each. The original list will always start with zero. So if I had a list of [0,2,5,9] i would get a list of [0,2,7,16].

accumulateTime :: [Float] -> [Float]
accumulateTime (x:xs) = cadd????

i have other parts of this code doing things but i cant seem how to make this list.

Answer 1

Sounds like you want a variant of scanl, which is related to foldl, but creates a list of intermediate results. So while foldl (+) 0 sums a list, scanl (+) 0 creates a list of partial sums. Here, you probably want scanl1 (+), which doesn’t add an extra zero at the beginning.

Prelude> scanl1 (+) [0, 2, 5, 9]
[0,2,7,16]