19.24 Module Queue: first-in first-out queues


This module implements queues (FIFOs), with in-place modification.
type 'a t
The type of queues containing elements of type 'a.
exception Empty
Raised when take is applied to an empty queue.
val create: unit -> 'a t
Return a new queue, initially empty.
val add: 'a -> 'a t -> unit
add x q adds the element x at the end of the queue q.
val take: 'a t -> 'a
take q removes and returns the first element in queue q, or raises Empty if the queue is empty.
val peek: 'a t -> 'a
peek q returns the first element in queue q, without removing it from the queue, or raises Empty if the queue is empty.
val clear : 'a t -> unit
Discard all elements from a queue.
val length: 'a t -> int
Return the number of elements in a queue.
val iter: f:('a -> unit) -> 'a t -> unit
iter f q applies f in turn to all elements of q, from the least recently entered to the most recently entered. The queue itself is unchanged.