[Haskell-cafe] Re: Possible Improvements

PR Stanley wrote:

data Tree = Leaf Int | Node Tree Int Tree

occurs :: Int -> Tree -> Bool occurs m (Leaf n) = m == n occurs m (Node l n r) = m == n || occurs m l || occurs m r

It works but I'd like to know if it can be improved in any way.

That's entirely fine. The logical or || doesn't evaluate it's second argument occurs m r if the first argument occurs m l turns out to be already True. In other words, thanks to lazy evaluation, the search stops if m has been found in the left subtree, it won't search the right subtree anymore. Regards, apfelmus