I think that your definition of size is not what you say it is. I guess that you expect (size (1 :> [2 :> [ 3 :> [] ] ])) to be 3. To count leaves you may start with something like: countleaves (_ :> []) = 1 You have then to define countleaves for the case it's not a leaf. I hope this is of some help. On Sun, 2015-12-20 at 20:59 +0100, Lorenzo Isella wrote:
Dear All, This is where I stand now. Please consider the short snippet
data Rose a = a :> [Rose a] deriving (Eq, Show)
root (a :> rs) = a
children (a :> rs) = rs
size :: Rose a -> Int
size (a :> rs) = 1 + (length $ children (a :> rs))
which defines a rose tree structure and the functions to get the root, the children and the size (i.e. number of nodes) of the rose tree. I would like to find the number of leaves (i.e. terminal nodes) in my rose tree. Essentially, I need to count the number of "[]" inside my rose tree definition. For instance, consider
mytree = (1 :> [2 :> [], 3 :> []])
which has exactly two leaves. Can anyone help me implement a function to get the number of leaves? Many thanks
Lorenzo _______________________________________________ Beginners mailing list Beginners@haskell.org http://mail.haskell.org/cgi-bin/mailman/listinfo/beginners