Re: [Haskell-cafe] How to do this in FP way?

"Magicloud Magiclouds" writes:

static int old; int diff (int now) { /* this would be called once a second */ int ret = now - old; old = now; return ret; }

Because there is no "variable" in Haskell. So how to do this in a FP way?

I would claim the FP way is like this: -- | Repeatedly subtract values from a baseline, returning a list -- containing each intermediate result diff :: Int -> [Int] -> [Int] diff = scanl (-) Prelude> diff 100 [1..10] [100,99,97,94,90,85,79,72,64,55,45] -k -- If I haven't seen further, it is by standing in the footprints of giants