#undef

1 files changed, 7 insertions, 4 deletions

diff --git a/tree.sig b/tree.sig
index 8caf4cc..a1ebf86 100644
--- a/tree.sig
+++ b/tree.sig
@@ -3,11 +3,14 @@ signature TREE = sig
 
   val empty: ('k, 'v) t
 
-  val insert: ('k -> 'k -> order) -> ('k, 'v) t -> 'k -> 'v
-        -> 'v option * ('k, 'v) t
+  type 'k cmp = 'k -> 'k -> order
 
-  val lookup: ('k -> 'k -> order) -> ('k, 'v) t -> 'k -> 'v option
-  val lookup2: ('k -> 'k -> order) -> ('k, 'v) t -> 'k ->
+  val insert: 'k cmp -> ('k, 'v) t -> 'k -> 'v -> 'v option * ('k, 'v) t
+
+  val delete: 'k cmp -> ('k, 'v) t -> 'k -> 'v option * ('k, 'v) t
+
+  val lookup: 'k cmp -> ('k, 'v) t -> 'k -> 'v option
+  val lookup2: 'k cmp -> ('k, 'v) t -> 'k ->
         ('v -> 'v option * 'a) * 'a -> 'a * ('k, 'v) t
 
   val print: ('k, 'v) t -> ('k -> string) -> ('v -> string) -> unit