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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.
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The ++ operator is the list concatenation operator which takes two lists as operands and "combines" them into a single list. So if you have the list [x] and the list [y] then you can concatenate them like this: [x]++[y] to get [x, y ]. Notice that : takes an element and a list while ++ takes two lists.
Internally, Haskell lists are represented as linked cons-cells. A cons-cell is like a C struct with two pointer fields head and tail. The head field points to the first element of the list, the tail field to the rest of the list.
If show is ok to print your elements, you can use putStr ( unlines $ map show [(1,"A"),(2,"B"),(3,"C"),(4,"D")]) but you can replace show by any funtion that'll take your custom type and return a string.
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]
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