add a generating thunk for split

1 files changed, 7 insertions, 4 deletions

diff --git a/doc/mcgoron.weight-balanced-trees.internal.scm b/doc/mcgoron.weight-balanced-trees.internal.scm
index 176d18e..8baf5e7 100644
--- a/doc/mcgoron.weight-balanced-trees.internal.scm
+++ b/doc/mcgoron.weight-balanced-trees.internal.scm
@@ -52,16 +52,19 @@ with `data`."))
 
 Returns a new tree with the elements of `left` and `right`."))
  ((name . "split")
-  (signature lambda ((comparator? cmp) (wb-tree-node? tree) key)
-             => (values wb-tree-node? boolean? wb-tree-node?))
+  (signature lambda ((comparator? cmp) (wb-tree-node? tree) key (procedure? default))
+             => (values wb-tree-node? * wb-tree-node?))
   "
 * It is an error if any element of `tree` is not comparable by `cmp`.
 * It is an error if `key` is not comparable by `cmp`.
 * It is an error if `cmp` does not have an order.
+* It is an error if `default` is not a thunk.
 
 Returns two trees, one of all values to the left of `key`, and one with
-all values to the right of `key`. The boolean is true if the key was
-found and false otherwise.")
+all values to the right of `key`.
+
+If a value that compares equal to `key` is found, that value is returned.
+Otherwise the result of calling `default` with no arguments is returned.")
  ((name . "search")
   (signature case-lambda ((((wb-tree-node? tree) (comparator? cmp) key) *)
                           (((wb-tree-node? tree) (comparator? cmp) key (procedure? default)) *)))