containers-0.4.0.0: Assorted concrete container types

Portability | portable
Stability | experimental
Maintainer | libraries@haskell.org

Data.Tree

Contents

- Two-dimensional drawing
- Extraction
- Building trees

Description

Multi-way trees (aka rose trees) and forests.

Synopsis

- data Tree a = Node {
  - rootLabel :: a
  - subForest :: Forest a
  }
- type Forest a = [Tree a]
- drawTree :: Tree String -> String
- drawForest :: Forest String -> String
- flatten :: Tree a -> [a]
- levels :: Tree a -> [[a]]
- unfoldTree :: (b -> (a, [b])) -> b -> Tree a
- unfoldForest :: (b -> (a, [b])) -> [b] -> Forest a
- unfoldTreeM :: Monad m => (b -> m (a, [b])) -> b -> m (Tree a)
- unfoldForestM :: Monad m => (b -> m (a, [b])) -> [b] -> m (Forest a)
- unfoldTreeM_BF :: Monad m => (b -> m (a, [b])) -> b -> m (Tree a)
- unfoldForestM_BF :: Monad m => (b -> m (a, [b])) -> [b] -> m (Forest a)

# Documentation

data Tree a

Multi-way trees, also known as rose trees.

Constructors

Node |

Fields

rootLabel :: a

  label value

subForest :: Forest a

  zero or more child trees

Instances

Monad Tree |
Functor Tree |
Typeable1 Tree |
Applicative Tree |
Foldable Tree |
Traversable Tree |
Eq a => Eq (Tree a) |
Data a => Data (Tree a) |
Read a => Read (Tree a) |
Show a => Show (Tree a) |

type Forest a = [Tree a]

# Two-dimensional drawing

drawTree :: Tree String -> String

Neat 2-dimensional drawing of a tree.

drawForest :: Forest String -> String

Neat 2-dimensional drawing of a forest.

# Extraction

flatten :: Tree a -> [a]

The elements of a tree in pre-order.

levels :: Tree a -> [[a]]

Lists of nodes at each level of the tree.

# Building trees

unfoldTree :: (b -> (a, [b])) -> b -> Tree a

Build a tree from a seed value

unfoldForest :: (b -> (a, [b])) -> [b] -> Forest a

Build a forest from a list of seed values

unfoldTreeM :: Monad m => (b -> m (a, [b])) -> b -> m (Tree a)

Monadic tree builder, in depth-first order

unfoldForestM :: Monad m => (b -> m (a, [b])) -> [b] -> m (Forest a)

Monadic forest builder, in depth-first order

unfoldTreeM_BF :: Monad m => (b -> m (a, [b])) -> b -> m (Tree a)

Monadic tree builder, in breadth-first order, using an algorithm adapted from Breadth-First Numbering: Lessons from a Small Exercise in Algorithm Design, by Chris Okasaki, ICFP'00.

unfoldForestM_BF :: Monad m => (b -> m (a, [b])) -> [b] -> m (Forest a)

Monadic forest builder, in breadth-first order, using an algorithm adapted from Breadth-First Numbering: Lessons from a Small Exercise in Algorithm Design, by Chris Okasaki, ICFP'00.