tree.hs

data Tree a = EmptyTree | Node a (Tree a) (Tree a) deriving (Show)

createTree :: (Ord a) => a -> Tree a
createTree x = Node x EmptyTree EmptyTree

insert :: (Ord a) => Tree a -> a -> Tree a
insert EmptyTree x = Node x EmptyTree EmptyTree
insert (Node x left right) y
  | x == y = Node x left right
  | x > y  = Node x (insert left y) right
  | otherwise = Node x left (insert right y)

find :: (Ord a) => Tree a -> a -> Bool
find EmptyTree x = False
find (Node x left right) y
  | x == y = True
  | x < y = find right y
  | otherwise = find left y

toList ::(Ord a) => Tree a -> [a]
toList EmptyTree = []
toList (Node x left right) = (toList left) ++ [x] ++ (toList right)

instance Functor Tree where
  fmap _ EmptyTree = EmptyTree
  fmap f (Node x left right) = Node (f x) (fmap f left) (fmap f right)