gistfile1.txt

data Tree a = EmptyTree | Node a (Tree a) (Tree a) deriving (Show, Read, Eq)


singleton :: a -> Tree a
singleton x = Node x EmptyTree EmptyTree

treeInsert :: (Ord a) => a -> Tree a -> Tree a
treeInsert x EmptyTree = singleton x
treeInsert x (Node a left right)
  | x == a = Node x left right
  | x < a = Node a (treeInsert x left) right
  | x > a = Node a left (treeInsert x right)
  
treeElem :: (Ord a) => a -> Tree a -> Bool
treeElem x EmptyTree = False
treeElem x (Node a left right)
  | x == a = True
  | x < a = treeElem x left
  | x > a = treeElem x right
  
  

nums = [8,6,4,1,7,3,5]
n = treeInsert 5 EmptyTree
a = treeInsert 30 n
c = treeInsert 93 a
numsTree = foldr treeInsert EmptyTree nums


res = map (+1) [1,2,3,4,5]
f :: Maybe a -> Maybe b
f Nothing   = Nothing
f (Just x)  = Just (x * 2)



main = print (res)