Philip, you wrote: ------------------------------------------------------------------------------------- I am trying to learn Haskell. As an exercise, I wrote a function to create a binary tree in level-order. I am attaching the code. I am sure there are a number of places where the code could be improved. Could you please point these out? Thanks, Philip
countNodes :: Tree a -> Integer countNodes Empty = 0 countNodes (Tree rootNode left right) = 1 + countNodes left + countNodes right
Stylistically, this is usually written using a fold. Try writing a function fold :: (a -> b -> b -> b) -> b -> Tree a -> b Then rewrite countNodes as countNodes = fold f 0 where f x left right = 1 + left + right A huge number of other handy functions can then be written in terms of fold. -- Chad Scherrer "Time flies like an arrow; fruit flies like a banana" -- Groucho Marx