Type of elements contained in the priority queue.

Type of priority queues.

The empty priority queue. Contains no elements.

is_empty q evaluates to true iff q is empty.

add e q evaluates to a new priority queue, which contains all the elements of q, and the additional element e.

union q q' evaluates to a new priority queue, which contains all the elements of both q and q'.

find_min q evaluates to the minimum element of q if it is not empty, and raises Not_found otherwise.

lookup_min q evaluates to Some e, where e is the minimum element of q, if q is not empty, and evaluates to None otherwise.

remove_min q evaluates to a new priority queue, which contains all the elements of q except for its minimum element. Raises Not_found if q is empty.

size q evaluates to the number of elements in q.