hi I was curious as to whether my implementation of a Rose Tree and a sumTree function was correct. The aumTree adds up the elements of a tree. data Tree a = Leaf a | Node [Tree a] sumTree :: Tree Int -> Int sumTree (Node []) = 0 sumTree (Node xs) = sum (map sumTree xs) The problem with this is I get a pattern matching error. Am I representing trees right... see below. Also, would an empty tree be represented by ... Node [] with this implementation? How would I represent a tree of the form... Tree (Node 2(Node 6 Empty Empty) Empty) taken from a binary one. Like this? Node [ [Leaf 2], Node [ Leaf 6,Node[],Node[] ], Node[] ] Ryan _________________________________________________________________ Find the best and worst places on the planet http://clk.atdmt.com/UKM/go/101719807/direct/01/