--- a/lib/ur/list.urs	Sat May 23 10:14:51 2009 -0400
+++ b/lib/ur/list.urs	Tue May 26 12:25:06 2009 -0400
@@ -4,9 +4,17 @@
 
 val rev : a ::: Type -> t a -> t a
 
+val revAppend : a ::: Type -> t a -> t a -> t a
+
+val append : a ::: Type -> t a -> t a -> t a
+
 val mp : a ::: Type -> b ::: Type -> (a -> b) -> t a -> t b
 
+val mapPartial : a ::: Type -> b ::: Type -> (a -> option b) -> t a -> t b
+
 val mapX : a ::: Type -> ctx ::: {Unit} -> (a -> xml ctx [] []) -> t a -> xml ctx [] []
 
 val mapM : m ::: (Type -> Type) -> monad m -> a ::: Type -> b ::: Type
            -> (a -> m b) -> list a -> m (list b)
+
+val filter : a ::: Type -> (a -> bool) -> t a -> t a