# (lispkit heap)
Library `(lispkit heap)` provides an implementation of a *priority queue* in form of a *binary max heap*. A *max heap* is a tree-based data structure in which for any given node *C*, if *P* is a parent node of *C*, then the value of *P* is greater than or equal to the value of *C*. Heaps as implemented by `(lispkit heap)` are mutable objects.
***
**heap-type-tag** 
Symbol representing the `heap` type. The `type-for` procedure of library `(lispkit type)` returns this symbol for all heap objects.
**(make-heap *****pred\
Returns a new empty binary max heap with *pred\
Returns `#t` if the heap *hp* is empty, otherwise `#f` is returned.
**(heap-max *****hp*****)** 
Returns the largest item in heap *hp*, i.e. the item which is larger than all others according to the comparison function of *hp*. Note, `heap-max` does not remove the largest item as opposed to `heap-delete-max!`. If there are no items on the heap, an error is signaled.
**(heap-add! *****hp e1 ...*****)**
Inserts an item into the heap. The same item can be inserted multiple times.
**(heap-delete-max! *****hp*****)**
Returns the largest item in heap *hp*, i.e. the item which is larger than all others according to the comparison function of *hp*, and removes the item from the heap. If there are no items on the heap, an error is signaled.
**(heap-clear! *****hp*****)**
Removes all items from *hp*. After this procedure has been executed, the heap is empty.
**(heap-copy *****hp*****)**
Returns a copy of heap *hp*.
**(heap->vector *****hp*****)**
Returns a new vector containing all items of the heap *hp* in descending order. This procedure does not mutate *hp*.
**(heap->list *****hp*****)**
Returns a list containing all items of the heap *hp* in descending order.
**(heap->reversed-list *****hp*****)**
Returns a list containing all items of the heap *hp* in ascending order.
**(list->heap! *****hp items*****)**
Inserts all the items from list *items* into heap *hp*.
**(list->heap *****items pred\
Creates a new heap for the given ordering predicate *pred\heap` returns the new heap.
**(vector->heap *****vec pred\
Creates and returns a new heap for the given ordering predicate *pred\
```
The question should be specific, self-contained, and written in natural language.
The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.
Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.