[Haskell] Binary Tree Traversal.

data BinTree a = Nil | Node a (BinTree a) (BinTree a) inorder2 :: BinTree a -> [a] -> [a] inorder2 Nil xs = [] inorder2 (Node val b1 b2) xs = (inorder2 b1 (val:(inorder2 b2 (xs)))) I want to be able to traverse across the binary tree in order and that is what I have so far. But somehow it always return []. it seems to ignore the "val:" Y. C.