Haskell Tree example, Haskell

Haskell Tree example

--ghc 7.10

main = putStr$show$maketree [1,2,5,7,4,5,3,2,8,6]

-- Tree

data Tree a = Empty | Node { v::a, l::Tree a, r::Tree a }

-- maketree

insert x Empty = Node x Empty Empty
insert x t@(Node v l r) = case compare x v of
                          GT -> Node v l (insert x r)
                          LT -> Node v (insert x l) r
                          EQ -> t
                          
maketree = foldr insert Empty

-- show Tree

instance (Show a) => Show (Tree a) where
  show t = foldr (++) "" [showline n t | n <- [1..depth t]]
  
tmux Empty z _ = z
tmux _ _ v     = v

depth t = tmux t 0 $ 1 + max (depth$l t) (depth$r t)
sep t   = tmux t "" " "
space s = replicate (length s) ' '
under s = replicate (length s) '_'

showt _ _ _ _ Empty = ""
showt sl sv sr 1 t = (sl$l t) ++ (sv$v t) ++ (sr$r t)
showt sl sv sr n t = (st$l t) ++ (sep$l t) ++ (space$show$v t) ++ (sep$r t) ++ (st$r t)
                     where st = showt sl sv sr (n-1)
                     
showvals n = showt (space.divl) show (space.divr) n
showdivs n = showt divl (space.show) divr n

divl t = tmux t "" $ (space ((divl$l t) ++ (show$v t))) ++ (under$divr$r t) ++ "/"
divr t = tmux t "" $ "\\" ++ (under$divl$l t) ++ (space ((show$v t) ++ (divr$r t)))

showline n t = (showvals n t) ++ "\n" ++ (showdivs n t) ++ "\n"


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