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# (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.
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**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\