add heap sequencing fns to data/heap

collects/data/heap.rkt

@@ -160,13 +160,14 @@
   (in-heap/consume! (heap-copy h)))
 
 (define (in-heap/consume! h)
-  (lambda ()
-    (values (lambda () (heap-min h))
-            (lambda () (heap-remove-min! h) #t)
-            #t
-            (lambda (_) (> (heap-count h) 0))
-            (lambda _ #t)
-            (lambda _ #t))))
+  (make-do-sequence
+   (lambda ()
+     (values (lambda (_) (heap-min h))
+             (lambda (_) (heap-remove-min! h) #t)
+             #t
+             (lambda (_) (> (heap-count h) 0))
+             (lambda _ #t)
+             (lambda _ #t)))))
 
 ;; --------
 
@@ -204,4 +205,7 @@
  [heap->vector (-> heap? vector?)]
  [heap-copy (-> heap? heap?)]
 
- [heap-sort! (-> procedure? vector? void?)])
+ [heap-sort! (-> procedure? vector? void?)]
+ 
+ [in-heap (-> heap? sequence?)]
+ [in-heap/consume! (-> heap? sequence?)])

collects/data/scribblings/heap.scrbl

@@ -78,3 +78,34 @@ Makes a copy of heap @racket[h].
 
 Sorts vector @racket[v] using the comparison function @racket[<=?].
 }
+
+
+
+@defproc[(in-heap/consume! [heap heap?]) sequence?]{
+Returns a sequence equivalent to @racket[heap], maintaining the heap's ordering. 
+The heap is consumed in the process. Equivalent to repeated calling 
+@racket[heap-min], then @racket[heap-remove-min!].
+
+  @examples[#:eval the-eval
+            (define h (make-heap <=))
+            (heap-add-all! h '(50 40 10 20 30))
+            
+            (for ([x (in-heap/consume! h)])
+              (displayln x))
+                            
+            (heap-count h)]
+}
+@defproc[(in-heap [heap heap?]) sequence?]{
+Returns a sequence equivalent to @racket[heap], maintaining the heap's ordering.
+Equivalent to @racket[in-heap/consume!] except the heap is copied first.
+
+  @examples[#:eval the-eval
+            (define h (make-heap <=))
+            (heap-add-all! h '(50 40 10 20 30))
+            
+            (for ([x (in-heap h)])
+              (displayln x))
+                            
+            (heap-count h)]
+}
+

collects/tests/data/heap.rkt

@@ -67,3 +67,21 @@
 
 (test-case "heap random dense"
   (rand-test 20 100 50 100))
+
+(test-equal? "in-heap"
+  (for/list ([x (in-heap (mkheap))]) x)
+  '(2 4 6 8 10))
+(test-equal? "post in-heap count"
+   (let* ([h (mkheap)]
+          [lst (for/list ([x (in-heap h)]) x)])
+     (heap-count h))
+   (heap-count (mkheap)))
+(test-equal? "in-heap/consume!"
+  (for/list ([x (in-heap/consume! (mkheap))]) x)
+  '(2 4 6 8 10))
+(test-equal? "post in-heap/consume! count"
+   (let* ([h (mkheap)]
+          [lst (for/list ([x (in-heap/consume! h)]) x)])
+     (heap-count h))
+   0)
+