I haven't tested it, but I think you're looking for something like this:
searchTree2 :: (a -> Bool) -> TreeLoc a -> Maybe (TreeLoc a)
searchTree2 pred rootLoc =
if pred (getLabel rootLoc)
then Just rootLoc
else firstChild rootLoc >>= siblings
where siblings loc = searchTree2 pred loc `mplus`
(searchTree2 pred =<< right loc)
On Mon, Mar 8, 2010 at 1:11 PM, Jian Fan <abe...@gmail.com> wrote:
> Hi,
>
> There doesn't seem to be a function to search the tree so
> I come up with following function:
>
> searchTree :: (a -> Bool) -> TreeLoc a -> Maybe (TreeLoc a)
> searchTree pred rootLoc =
> if pred (getLabel rootLoc) then
> Just rootLoc
> else case firstChild rootLoc of
> Just loc -> case searchTree pred loc of
> Just loc -> Just loc
> Nothing -> case right loc of
> Just rLoc -> searchTree pred rLoc
> Nothing -> Nothing
> Nothing -> Nothing
>
> Which feels quite ugly. Any suggestions? Thanks.
>
> Jian
>
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