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





Description 
Queues with constant time operations, from
Simple and efficient purely functional queues and deques,
by Chris Okasaki, JFP 5(4):583592, October 1995.


Synopsis 



Documentation 

data Queue a 
The type of FIFO queues.
 Instances  


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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