--- a/lib/top.ur	Sun Sep 14 11:02:18 2008 -0400
+++ b/lib/top.ur	Sun Sep 14 15:10:04 2008 -0400
@@ -1,9 +1,21 @@
 con idT = fn t :: Type => t
 con record = fn t :: {Type} => $t
+con fstTT = fn t :: (Type * Type) => t.1
+con sndTT = fn t :: (Type * Type) => t.2
 
 con mapTT (f :: Type -> Type) = fold (fn nm t acc => [nm] ~ acc =>
         [nm = f t] ++ acc) []
 
+con mapT2T (f :: (Type * Type) -> Type) = fold (fn nm t acc => [nm] ~ acc =>
+        [nm = f t] ++ acc) []
+
+con ex = fn tf :: (Type -> Type) =>
+        res ::: Type -> (choice :: Type -> tf choice -> res) -> res
+
+fun ex (tf :: (Type -> Type)) (choice :: Type) (body : tf choice) : ex tf =
+        fn (res ::: Type) (f : choice :: Type -> tf choice -> res) =>
+                f [choice] body
+
 fun compose (t1 ::: Type) (t2 ::: Type) (t3 ::: Type) (f1 : t2 -> t3) (f2 : t1 -> t2) (x : t1) = f1 (f2 x)
 
 fun txt (t ::: Type) (ctx ::: {Unit}) (use ::: {Type}) (sh : show t) (v : t) = cdata (show sh v)
@@ -18,6 +30,16 @@
                         fn r => f [nm] [t] [rest] r.nm (acc (r -- nm)))
                 (fn _ => i)
 
+fun foldT2R (tf :: (Type * Type) -> Type) (tr :: {(Type * Type)} -> Type)
+        (f : nm :: Name -> t :: (Type * Type) -> rest :: {(Type * Type)} -> [nm] ~ rest
+                -> tf t -> tr rest -> tr ([nm = t] ++ rest))
+        (i : tr []) =
+        fold [fn r :: {(Type * Type)} => $(mapT2T tf r) -> tr r]
+                (fn (nm :: Name) (t :: (Type * Type)) (rest :: {(Type * Type)}) (acc : _ -> tr rest) =>
+                        [[nm] ~ rest] =>
+                        fn r => f [nm] [t] [rest] r.nm (acc (r -- nm)))
+                (fn _ => i)
+
 fun foldTR2 (tf1 :: Type -> Type) (tf2 :: Type -> Type) (tr :: {Type} -> Type)
         (f : nm :: Name -> t :: Type -> rest :: {Type} -> [nm] ~ rest
                 -> tf1 t -> tf2 t -> tr rest -> tr ([nm = t] ++ rest))
@@ -28,6 +50,16 @@
                         fn r1 r2 => f [nm] [t] [rest] r1.nm r2.nm (acc (r1 -- nm) (r2 -- nm)))
                 (fn _ _ => i)
 
+fun foldT2R2 (tf1 :: (Type * Type) -> Type) (tf2 :: (Type * Type) -> Type) (tr :: {(Type * Type)} -> Type)
+        (f : nm :: Name -> t :: (Type * Type) -> rest :: {(Type * Type)} -> [nm] ~ rest
+                -> tf1 t -> tf2 t -> tr rest -> tr ([nm = t] ++ rest))
+        (i : tr []) =
+        fold [fn r :: {(Type * Type)} => $(mapT2T tf1 r) -> $(mapT2T tf2 r) -> tr r]
+                (fn (nm :: Name) (t :: (Type * Type)) (rest :: {(Type * Type)}) (acc : _ -> _ -> tr rest) =>
+                        [[nm] ~ rest] =>
+                        fn r1 r2 => f [nm] [t] [rest] r1.nm r2.nm (acc (r1 -- nm) (r2 -- nm)))
+                (fn _ _ => i)
+
 fun foldTRX (tf :: Type -> Type) (ctx :: {Unit})
         (f : nm :: Name -> t :: Type -> rest :: {Type} -> [nm] ~ rest
                 -> tf t -> xml ctx [] []) =
@@ -37,6 +69,15 @@
                         fn r acc => <xml>{f [nm] [t] [rest] r}{acc}</xml>)
                 <xml></xml>
 
+fun foldT2RX (tf :: (Type * Type) -> Type) (ctx :: {Unit})
+        (f : nm :: Name -> t :: (Type * Type) -> rest :: {(Type * Type)} -> [nm] ~ rest
+                -> tf t -> xml ctx [] []) =
+        foldT2R [tf] [fn _ => xml ctx [] []]
+                (fn (nm :: Name) (t :: (Type * Type)) (rest :: {(Type * Type)}) =>
+                        [[nm] ~ rest] =>
+                        fn r acc => <xml>{f [nm] [t] [rest] r}{acc}</xml>)
+                <xml></xml>
+
 fun foldTRX2 (tf1 :: Type -> Type) (tf2 :: Type -> Type) (ctx :: {Unit})
         (f : nm :: Name -> t :: Type -> rest :: {Type} -> [nm] ~ rest
                 -> tf1 t -> tf2 t -> xml ctx [] []) =
@@ -46,6 +87,15 @@
                         fn r1 r2 acc => <xml>{f [nm] [t] [rest] r1 r2}{acc}</xml>)
                 <xml></xml>
 
+fun foldT2RX2 (tf1 :: (Type * Type) -> Type) (tf2 :: (Type * Type) -> Type) (ctx :: {Unit})
+        (f : nm :: Name -> t :: (Type * Type) -> rest :: {(Type * Type)} -> [nm] ~ rest
+                -> tf1 t -> tf2 t -> xml ctx [] []) =
+        foldT2R2 [tf1] [tf2] [fn _ => xml ctx [] []]
+                (fn (nm :: Name) (t :: (Type * Type)) (rest :: {(Type * Type)}) =>
+                        [[nm] ~ rest] =>
+                        fn r1 r2 acc => <xml>{f [nm] [t] [rest] r1 r2}{acc}</xml>)
+                <xml></xml>
+
 fun queryX (tables ::: {{Type}}) (exps ::: {Type}) (ctx ::: {Unit}) (q : sql_query tables exps) =
         [tables ~ exps] =>
         fn (f : $(exps ++ fold (fn nm (fields :: {Type}) acc => [nm] ~ acc => [nm = $fields] ++ acc) [] tables)