Haskell Hierarchical Libraries (base package) Contents Index

Data.Tree Portability portable Stability experimental Maintainer libraries@haskell.org

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 rootLabel :: a label value subForest :: (Forest a) zero or more child trees Instances Eq a => Eq (Tree a) Read a => Read (Tree a) Show a => Show (Tree a) Functor Tree

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 Breadth­First 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 Breadth­First Numbering: Lessons from a Small Exercise in Algorithm Design, by Chris Okasaki, ICFP'00.

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