Balanced Binary Tree from List in Haskell.... Literally just copying the definition.

binarytree.hs

data Tree a = Leaf
            | Node Integer (Tree a) a (Tree a)
            deriving (Show, Eq)

foldTree :: [a] -> Tree a
foldTree [] = Leaf
foldTree xs = Node height 
            (foldTree $ take half xs) 
        (xs !! half)
            (foldTree $ drop (half + 1) xs)
        where 
            len = length xs
            half = len `div` 2
            height = floor $ logBase 2 (fromIntegral len)