--- a/src/ur/openid.urs	Wed Dec 29 14:17:27 2010 -0500
+++ b/src/ur/openid.urs	Wed Dec 29 14:38:56 2010 -0500
@@ -1,6 +1,12 @@
 datatype association_type = HMAC_SHA1 | HMAC_SHA256
 datatype association_session_type = NoEncryption | DH_SHA1 | DH_SHA256
+datatype authentication = AuthenticatedAs of string | Canceled | Failure of string
 
-val authenticate : association_type -> association_session_type -> string -> transaction string
+val authenticate : (authentication -> transaction page)
+                   -> {AssociationType : association_type,
+                       AssociationSessionType : association_session_type,
+                       Identifier : string}
+                   -> transaction string
 (* Doesn't return normally if everything goes as planned.
- * Instead, the user is redirected to his OP to authenticate there. *)
+ * Instead, the user is redirected to his OP to authenticate there.
+ * Later, the function passed as the first argument should be called with the result. *)