On Tue, Nov 3, 2009 at 1:42 PM, Martijn van Steenbergen <mart...@van.steenbergen.nl> wrote: > Dear café, > > I am looking for a function that does an N-dimensional diagonal traversal. I > want the traversal to be fair: the sum of the indices of the produced > combinations should be non-decreasing. Let me illustrate with an example. > > The type of a 2-dimensional traversal would look like this: >> >> diag2 :: [a] -> [b] -> [(a, b)]
I believe you can get what you want using the diagonal function from Control.Monad.Omega. product xs ys = [ [ (x,y) | y <- ys ] | x <- xs ] diag2 xs ys = diagonal (product xs ys) I think if you separate taking the cartesian product and flattening it, like this, you might have an easier time wrangling all the different variants you want. Luke _______________________________________________ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
