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

Contents Primitive operations Queues and lists

Description

Queues with constant time operations, from Simple and efficient purely functional queues and deques, by Chris Okasaki, JFP 5(4):583-592, October 1995.

Synopsis

data Queue a emptyQueue :: Queue a addToQueue :: Queue a -> a -> Queue a deQueue :: Queue a -> Maybe (a, Queue a) listToQueue :: [a] -> Queue a queueToList :: Queue a -> [a]

Documentation

data Queue a

The type of FIFO queues. Instances Functor Queue

Primitive operations

Each of these requires O(1) time in the worst case.

emptyQueue :: Queue a

The empty queue.

addToQueue :: Queue a -> a -> Queue a

Add an element to the back of a queue.

deQueue :: Queue a -> Maybe (a, Queue a)

Attempt to extract the front element from a queue. If the queue is empty, Nothing, otherwise the first element paired with the remainder of the queue.

Queues and lists

listToQueue :: [a] -> Queue a

A queue with the same elements as the list.

queueToList :: Queue a -> [a]

The elements of a queue, front first.

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