Re: [Haskell-beginners] Is there an "unscan" function?

Is "speed x" at least a somewhat universal term for the number of list elements that get operated on per iteration? It works really well. I was also wondering about what you just pointed out: if there's a nice way to form (what I now know to call) speed >1 functions. Your form looks a lot nicer than some of the stranger things I've been coming up with. On Thu, Jan 12, 2012 at 1:37 AM, Stephen Tetley wrote:

Direct recursion is almost always clearer if you are traversing the list at a "different speed". The usual list functionals (map, filter, folds) are all speed 1 - traversing one element at a time. Here we want pairwise traversal:

unscan :: (a -> a -> b) -> [a] -> [b] unscan f (a:b:bs) = f a b : unscan f b bs unscan _ _ = []