A simple polymorphic functional double-ended queue. Use this if you need a queue-like
data structure that provides enqueue and dequeue accessors on both ends. For
strictly first-in, first-out access, see Fqueue
.
Amortized running times assume that enqueue/dequeue are used sequentially, threading the changing deque through the calls.
Checks whether the provided element is there, using polymorphic compare if equal
is not provided
fold t ~init ~f
returns f (... f (f (f init e1) e2) e3 ...) en
, where e1..en
are the elements of t
Returns true
if and only if there exists an element for which the provided
function evaluates to true
. This is a short-circuiting operation.
Returns true
if and only if the provided function evaluates to true
for all
elements. This is a short-circuiting operation.
Returns the number of elements for which the provided function evaluates to true.
Returns as an option
the first element for which f
evaluates to true.
Returns the first evaluation of f
that returns Some
, and returns None
if there
is no such element.
Returns a minimum (resp maximum) element from the collection using the provided
cmp
function, or None
if the collection is empty. In case of a tie, the first
element encountered while traversing the collection is returned. The implementation
uses fold
so it has the same complexity as fold
.
The empty deque.
A one-element deque.
of_list
returns a deque with elements in the same front-to-back order as the
list.
peek t side
produces Some
of the element at the side
of t
, or None
if t
is
empty.
Complexity: worst-case O(1).