36 lines
1.4 KiB
Haskell
36 lines
1.4 KiB
Haskell
import Data.Tree (Tree,Forest(..))
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import qualified Data.Tree as Tree
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data BinTree a = Empty
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| Node a (BinTree a) (BinTree a)
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deriving (Eq,Ord,Show)
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treeFromList :: (Ord a) => [a] -> BinTree a
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treeFromList [] = Empty
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treeFromList (x:xs) = Node x (treeFromList (filter (<x) xs))
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(treeFromList (filter (>x) xs))
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-- | Function to transform our internal BinTree type to the
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-- type of Tree declared in Data.Tree (from containers package)
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-- so that the function Tree.drawForest can use
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binTreeToForestString :: (Show a) => BinTree a -> Forest String
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binTreeToForestString Empty = []
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binTreeToForestString (Node x left right) =
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[Tree.Node (show x) ((binTreeToForestString left) ++ (binTreeToForestString right))]
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-- | Function that given a BinTree print a representation of it in the console
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prettyPrintTree :: (Show a) => BinTree a -> IO ()
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prettyPrintTree = putStrLn . Tree.drawForest . binTreeToForestString
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main = do
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putStrLn "Int binary tree:"
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prettyPrintTree $ treeFromList [7,2,4,8,1,3,6,21,12,23]
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putStrLn "\nNote we could also use another type\n"
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putStrLn "String binary tree:"
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prettyPrintTree $
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treeFromList ["foo","bar","baz","gor","yog"]
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putStrLn "\nAs we can test equality and order trees, we can make tree of trees!\n"
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putStrLn "\nBinary tree of Char binary trees:"
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prettyPrintTree (treeFromList
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(map treeFromList ["foo","bar","zara","baz","foo"]))
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