Portability	portable
Stability	experimental
Maintainer	libraries@haskell.org
Safe Haskell	Safe

Data.Tree

Contents

Two-dimensional drawing
Extraction
Building trees

Description

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

Synopsis

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)
NFData a => NFData (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.