- | zero k m -> let (found,lt,gt) = splitLookup k l in (found,lt,union gt r)
- | otherwise -> let (found,lt,gt) = splitLookup k r in (found,union l lt,gt)
+ | m < 0 -> (if k >= 0 -- handle negative numbers.
+ then let (lt,found,gt) = splitLookup' k l in (union r lt,found, gt)
+ else let (lt,found,gt) = splitLookup' k r in (lt,found, union gt l))
+ | otherwise -> splitLookup' k t
+ Tip ky y
+ | k>ky -> (t,Nothing,Nil)
+ | k<ky -> (Nil,Nothing,t)
+ | otherwise -> (Nil,Just y,Nil)
+ Nil -> (Nil,Nothing,Nil)
+
+splitLookup' :: Key -> IntMap a -> (IntMap a,Maybe a,IntMap a)
+splitLookup' k t
+ = case t of
+ Bin p m l r
+ | nomatch k p m -> if k>p then (t,Nothing,Nil) else (Nil,Nothing,t)
+ | zero k m -> let (lt,found,gt) = splitLookup k l in (lt,found,union gt r)
+ | otherwise -> let (lt,found,gt) = splitLookup k r in (union l lt,found,gt)