revert change to set-delete

This solution is O(n). Since set-delete is basically set-difference,
this should only be used for small sets.

1 files changed, 7 insertions, 9 deletions

diff --git a/mcgoron/weight-balanced-trees/srfi/113/sets.scm b/mcgoron/weight-balanced-trees/srfi/113/sets.scm
index 964ff87..b3d6b13 100644
--- a/mcgoron/weight-balanced-trees/srfi/113/sets.scm
+++ b/mcgoron/weight-balanced-trees/srfi/113/sets.scm
@@ -104,15 +104,13 @@
 (define set-replace! set-replace)
 
 (define (set-delete-all set elements)
-  (define cmp (set-element-comparator set))
-  (define (delete node)
-    (if (null? node)
-        '()
-        (with-node (node data ("<" left) (">" right))
-          (if (member data elements (cute =? cmp <> <>))
-              (join2 (delete left) (delete right))
-              (join data (delete left) (delete right))))))
-  (raw-set cmp (delete (get-node set))))
+  (let ((cmp (set-element-comparator set)))
+    (raw-set
+     cmp
+     (fold (lambda (element node)
+             (delete cmp node element))
+           (get-node set)
+           elements))))
 (define set-delete-all! set-delete-all)
 
 (define (set-delete set . elements)