FYI: [Raymond]
... Q. Do other languages do it? A. Numpy, no. R, no. APL, no. Mathematica, no. Haskell, yes.
Haskell has millions of functions ;-) `mapAccumL` is a God-awful mixture of Python's map(), reduce(), and accumulate() :-( The examples here should convince you it's nearly incomprehensible: http://zvon.org/other/haskell/Outputlist/mapAccumL_f.html A more-than-less direct equivalent to Python's `accumulate` is Haskell's `scanl1`: http://zvon.org/comp/r/ref-Haskell.html#Functions~Prelude.scanl1 That doesn't allow specifying an initial value. But, Haskell being Haskell, the closely related `scanl` function requires specifying an initial value, which is also the first element of the list it returns: http://zvon.org/comp/r/ref-Haskell.html#Functions~Prelude.scanl Of the two, `scanl` is more basic - indeed, the Standard Prelude defines scanl1 by peeling off the first element of the list and passing it as the initial value for scanl to use scanl :: (a -> b -> a) -> a -> [b] -> [a] scanl f q xs = q : (case xs of [] -> [] x:xs -> scanl f (f q x) xs) scanl1 :: (a -> a -> a) -> [a] -> [a] scanl1 f (x:xs) = scanl f x xs scanl1 _ [] = [] There are also analogous `scanr` and `scanr1` functions for doing "right-to-left" accumulation. So, bottom line: as usual, when looking to Haskell for prior art,, "all of the above - for a start" applies ;-)