all tasks

Task/Visualize-a-tree/Haskell/visualize-a-tree.hs

@@ -0,0 +1,15 @@
+data Tree a = Empty | Node { value :: a, left :: Tree a, right :: Tree a }
+	deriving (Show, Eq)
+
+tree = Node 1 (Node 2 (Node 4 (Node 7 Empty Empty) Empty)
+	(Node 5 Empty Empty)) (Node 3 (Node 6 (Node 8 Empty Empty)
+	(Node 9 Empty Empty)) Empty)
+
+treeIndent Empty = ["-- (nil)"]
+treeIndent t = ["--" ++ show (value t)]
+	++ map ("  |"++) ls ++ ("  `" ++ r):map ("   "++) rs
+	where
+	(r:rs) = treeIndent$right t
+	ls     = treeIndent$left t
+
+main = mapM_ putStrLn $ treeIndent tree