1 files changed, 8 insertions, 0 deletions
diff --git a/lib/top.urs b/lib/top.urs
index 80344602..c2d2fc8f 100644
--- a/lib/top.urs
+++ b/lib/top.urs
@@ -1,3 +1,6 @@
+con idT = fn t :: Type => t
+con record = fn t :: {Type} => $t
+
 con mapTT = fn f :: Type -> Type => fold (fn nm t acc => [nm] ~ acc =>
         [nm = f t] ++ acc) []
 
@@ -6,3 +9,8 @@ val compose : t1 ::: Type -> t2 ::: Type -> t3 ::: Type
 
 val txt : t ::: Type -> ctx ::: {Unit} -> use ::: {Type} -> show t -> t
         -> xml ctx use []
+
+val foldTR2 : tf1 :: (Type -> Type) -> tf2 :: (Type -> Type) -> tr :: ({Type} -> Type)
+        -> (nm :: Name -> t :: Type -> rest :: {Type} -> [nm] ~ rest
+                -> tf1 t -> tf2 t -> tr rest -> tr ([nm = t] ++ rest))
+        -> tr [] -> r :: {Type} -> $(mapTT tf1 r) -> $(mapTT tf2 r) -> tr r