Visualize a tree: Difference between revisions

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=={{header|Haskell}}==

Tree borrowed from [[Tree traversal]]:

<lang haskell>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</lang>

{{out}}

<pre>

--1

|--2

| |--4

| | |--7

| | | |-- (nil)

| | | `-- (nil)

| | `-- (nil)

| `--5

| |-- (nil)

| `-- (nil)

`--3

|--6

| |--8

| | |-- (nil)

| | `-- (nil)

| `--9

| |-- (nil)

| `-- (nil)

`-- (nil)