Re: [Haskell-cafe] Re: Something like scan1

18 Jun 2008


      On Wed, 18 Jun 2008, Achim Schneider wrote:
...
Henning Thielemann  wrote:
...
On Wed, 18 Jun 2008, Achim Schneider wrote:
...
Is there a generalisation of scan1, such that eg.
foo (+) [0,1] (1,2) = [0,1,1,2,3,5,8,13,...]
?
What is the (1,2) for?
Specifying the relative indexes an element depends on. Ideally, it
should be generalised for n-ary functions.
foo f prefix (n,m) =
    let k = length prefix
        xs = prefix ++ zipWith f (xss!!(k-n)) (xss!!(k-m))
        xss = List.tails xs
    in  xs