Writer takes a generator, coroutines!

demo.scm

@@ -19,13 +19,11 @@
 		   (cdr pair))))
        graph))
 
-(define* (heap-unfold heap #:optional (infinites? #f))
-  (if (and (heap-peek heap) (or infinites? (finite? (car (heap-peek heap)))))
-      (cons (heap-peek heap) (heap-unfold (heap-pop heap) infinites?))
-      '()))
-
-(define graphs '())
-(djikstra graph 90 9 (lambda (visited heap)
-		       (set! graphs (cons (color-graph graph visited heap) graphs))))
-(write-graphs-to-file (reverse-list->vector graphs) "djikstra.webp")
+(define graph-generator
+  (make-generator
+   (lambda (yield)
+     (djikstra graph 90 9 (lambda (visited heap)
+			    (yield (color-graph graph visited heap))))
+     #f)))
 
+(write-graphs-to-file "djikstra.webp" graph-generator)