"Hello world" compiles, after replacing type-level fold with map

3 files changed, 33 insertions, 80 deletions

diff --git a/lib/ur/basis.urs b/lib/ur/basis.urs
index b4a40fde..cd2468ba 100644
--- a/lib/ur/basis.urs
+++ b/lib/ur/basis.urs
@@ -120,31 +120,20 @@ con sql_exp :: {{Type}} -> {{Type}} -> {Type} -> Type -> Type
 con sql_subset :: {{Type}} -> {{Type}} -> Type
 val sql_subset : keep_drop :: {({Type} * {Type})}
                               -> sql_subset
-                                     (fold (fn nm (fields :: ({Type} * {Type}))
-                                                  acc [[nm] ~ acc]
-                                                  [fields.1 ~ fields.2] =>
-                                               [nm = fields.1 ++ fields.2]
-                                                   ++ acc) [] keep_drop)
-                                     (fold (fn nm (fields :: ({Type} * {Type}))
-                                                  acc [[nm] ~ acc] =>
-                                               [nm = fields.1] ++ acc)
-                                               [] keep_drop)
+                                     (map (fn fields :: ({Type} * {Type}) => fields.1 ++ fields.2) keep_drop)
+                                     (map (fn fields :: ({Type} * {Type}) => fields.1) keep_drop)
 val sql_subset_all : tables :: {{Type}} -> sql_subset tables tables
 
 val sql_query1 : tables ::: {{Type}}
                  -> grouped ::: {{Type}}
                  -> selectedFields ::: {{Type}}
                  -> selectedExps ::: {Type}
-                 -> {From : $(fold (fn nm (fields :: {Type}) acc [[nm] ~ acc] =>
-                                       [nm = sql_table fields] ++ acc)
-                                       [] tables),
+                 -> {From : $(map (fn fields :: {Type} => sql_table fields) tables),
                      Where : sql_exp tables [] [] bool,
                      GroupBy : sql_subset tables grouped,
                      Having : sql_exp grouped tables [] bool,
                      SelectFields : sql_subset grouped selectedFields,
-                     SelectExps : $(fold (fn nm (t :: Type) acc [[nm] ~ acc] =>
-                                             [nm = sql_exp grouped tables [] t]
-                                                 ++ acc) [] selectedExps) }
+                     SelectExps : $(map (fn (t :: Type) => sql_exp grouped tables [] t) selectedExps) }
                  -> sql_query1 tables selectedFields selectedExps
 
 type sql_relop 
@@ -291,8 +280,7 @@ val query : tables ::: {{Type}} -> exps ::: {Type}
             -> fn [tables ~ exps] =>
                   state ::: Type
                   -> sql_query tables exps
-                  -> ($(exps ++ fold (fn nm (fields :: {Type}) acc [[nm] ~ acc] =>
-                                         [nm = $fields] ++ acc) [] tables)
+                  -> ($(exps ++ map (fn fields :: {Type} => $fields) tables)
                       -> state
                       -> transaction state)
                   -> state
@@ -306,17 +294,12 @@ val dml : dml -> transaction unit
 
 val insert : fields ::: {Type}
              -> sql_table fields
-             -> $(fold (fn nm (t :: Type) acc [[nm] ~ acc] =>
-                           [nm = sql_exp [] [] [] t] ++ acc)
-                           [] fields)
+             -> $(map (fn t :: Type => sql_exp [] [] [] t) fields)
              -> dml
 
 val update : unchanged ::: {Type} -> changed :: {Type} ->
              fn [changed ~ unchanged] =>
-                $(fold (fn nm (t :: Type) acc [[nm] ~ acc] =>
-                           [nm = sql_exp [T = changed ++ unchanged] [] [] t]
-                               ++ acc)
-                           [] changed)
+                $(map (fn t :: Type => sql_exp [T = changed ++ unchanged] [] [] t) changed)
                 -> sql_table (changed ++ unchanged)
                 -> sql_exp [T = changed ++ unchanged] [] [] bool
                 -> dml
diff --git a/lib/ur/top.ur b/lib/ur/top.ur
index 35e8519b..58e99f3c 100644
--- a/lib/ur/top.ur
+++ b/lib/ur/top.ur
@@ -8,17 +8,7 @@ con fstTTT (t :: (Type * Type * Type)) = t.1
 con sndTTT (t :: (Type * Type * Type)) = t.2
 con thdTTT (t :: (Type * Type * Type)) = t.3
 
-con mapTT (f :: Type -> Type) = fold (fn nm t acc [[nm] ~ acc] =>
-                                         [nm = f t] ++ acc) []
-
-con mapUT = fn f :: Type => fold (fn nm t acc [[nm] ~ acc] =>
-                                     [nm = f] ++ acc) []
-
-con mapT2T (f :: (Type * Type) -> Type) = fold (fn nm t acc [[nm] ~ acc] =>
-                                                   [nm = f t] ++ acc) []
-
-con mapT3T (f :: (Type * Type * Type) -> Type) = fold (fn nm t acc [[nm] ~ acc] =>
-                                                          [nm = f t] ++ acc) []
+con mapUT = fn f :: Type => map (fn _ :: Unit => f)
 
 con ex = fn tf :: (Type -> Type) =>
             res ::: Type -> (choice :: Type -> tf choice -> res) -> res
@@ -69,7 +59,7 @@ fun foldTR (tf :: Type -> Type) (tr :: {Type} -> Type)
                 -> fn [[nm] ~ rest] =>
                       tf t -> tr rest -> tr ([nm = t] ++ rest))
            (i : tr []) =
-    fold [fn r :: {Type} => $(mapTT tf r) -> tr r]
+    fold [fn r :: {Type} => $(map tf r) -> tr r]
              (fn (nm :: Name) (t :: Type) (rest :: {Type}) (acc : _ -> tr rest)
                               [[nm] ~ rest] r =>
                  f [nm] [t] [rest] r.nm (acc (r -- nm)))
@@ -80,7 +70,7 @@ fun foldT2R (tf :: (Type * Type) -> Type) (tr :: {(Type * Type)} -> Type)
                  -> fn [[nm] ~ rest] =>
                        tf t -> tr rest -> tr ([nm = t] ++ rest))
             (i : tr []) =
-    fold [fn r :: {(Type * Type)} => $(mapT2T tf r) -> tr r]
+    fold [fn r :: {(Type * Type)} => $(map tf r) -> tr r]
              (fn (nm :: Name) (t :: (Type * Type)) (rest :: {(Type * Type)})
                               (acc : _ -> tr rest) [[nm] ~ rest] r =>
                  f [nm] [t] [rest] r.nm (acc (r -- nm)))
@@ -91,7 +81,7 @@ fun foldT3R (tf :: (Type * Type * Type) -> Type) (tr :: {(Type * Type * Type)} -
                  -> fn [[nm] ~ rest] =>
                        tf t -> tr rest -> tr ([nm = t] ++ rest))
             (i : tr []) =
-    fold [fn r :: {(Type * Type * Type)} => $(mapT3T tf r) -> tr r]
+    fold [fn r :: {(Type * Type * Type)} => $(map tf r) -> tr r]
              (fn (nm :: Name) (t :: (Type * Type * Type)) (rest :: {(Type * Type * Type)})
                               (acc : _ -> tr rest) [[nm] ~ rest] r =>
                  f [nm] [t] [rest] r.nm (acc (r -- nm)))
@@ -102,7 +92,7 @@ fun foldTR2 (tf1 :: Type -> Type) (tf2 :: Type -> Type) (tr :: {Type} -> Type)
                  -> fn [[nm] ~ rest] =>
                        tf1 t -> tf2 t -> tr rest -> tr ([nm = t] ++ rest))
             (i : tr []) =
-    fold [fn r :: {Type} => $(mapTT tf1 r) -> $(mapTT tf2 r) -> tr r]
+    fold [fn r :: {Type} => $(map tf1 r) -> $(map tf2 r) -> tr r]
              (fn (nm :: Name) (t :: Type) (rest :: {Type})
                               (acc : _ -> _ -> tr rest) [[nm] ~ rest] r1 r2 =>
                  f [nm] [t] [rest] r1.nm r2.nm (acc (r1 -- nm) (r2 -- nm)))
@@ -114,7 +104,7 @@ fun foldT2R2 (tf1 :: (Type * Type) -> Type) (tf2 :: (Type * Type) -> Type)
                   -> fn [[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]
+    fold [fn r :: {(Type * Type)} => $(map tf1 r) -> $(map tf2 r) -> tr r]
              (fn (nm :: Name) (t :: (Type * Type)) (rest :: {(Type * Type)})
                               (acc : _ -> _ -> tr rest) [[nm] ~ rest] r1 r2 =>
                  f [nm] [t] [rest] r1.nm r2.nm (acc (r1 -- nm) (r2 -- nm)))
@@ -126,7 +116,7 @@ fun foldT3R2 (tf1 :: (Type * Type * Type) -> Type) (tf2 :: (Type * Type * Type)
                   -> fn [[nm] ~ rest] =>
                         tf1 t -> tf2 t -> tr rest -> tr ([nm = t] ++ rest))
              (i : tr []) =
-    fold [fn r :: {(Type * Type * Type)} => $(mapT3T tf1 r) -> $(mapT3T tf2 r) -> tr r]
+    fold [fn r :: {(Type * Type * Type)} => $(map tf1 r) -> $(map tf2 r) -> tr r]
              (fn (nm :: Name) (t :: (Type * Type * Type)) (rest :: {(Type * Type * Type)})
                               (acc : _ -> _ -> tr rest) [[nm] ~ rest] r1 r2 =>
                  f [nm] [t] [rest] r1.nm r2.nm (acc (r1 -- nm) (r2 -- nm)))
@@ -195,8 +185,7 @@ fun foldT3RX2 (tf1 :: (Type * Type * Type) -> Type) (tf2 :: (Type * Type * Type)
 
 fun queryX (tables ::: {{Type}}) (exps ::: {Type}) (ctx ::: {Unit})
            (q : sql_query tables exps) [tables ~ exps]
-           (f : $(exps ++ fold (fn nm (fields :: {Type}) acc [[nm] ~ acc] =>
-                                   [nm = $fields] ++ acc) [] tables)
+           (f : $(exps ++ map (fn fields :: {Type} => $fields) tables)
                 -> xml ctx [] []) =
     query q
           (fn fs acc => return <xml>{acc}{f fs}</xml>)
@@ -204,8 +193,7 @@ fun queryX (tables ::: {{Type}}) (exps ::: {Type}) (ctx ::: {Unit})
 
 fun queryX' (tables ::: {{Type}}) (exps ::: {Type}) (ctx ::: {Unit})
             (q : sql_query tables exps) [tables ~ exps]
-            (f : $(exps ++ fold (fn nm (fields :: {Type}) acc [[nm] ~ acc] =>
-                                    [nm = $fields] ++ acc) [] tables)
+            (f : $(exps ++ map (fn fields :: {Type} => $fields) tables)
                  -> transaction (xml ctx [] [])) =
     query q
           (fn fs acc =>
diff --git a/lib/ur/top.urs b/lib/ur/top.urs
index d6315b92..49aad50c 100644
--- a/lib/ur/top.urs
+++ b/lib/ur/top.urs
@@ -8,17 +8,7 @@ con fstTTT = fn t :: (Type * Type * Type) => t.1
 con sndTTT = fn t :: (Type * Type * Type) => t.2
 con thdTTT = fn t :: (Type * Type * Type) => t.3
 
-con mapTT = fn f :: Type -> Type => fold (fn nm t acc [[nm] ~ acc] =>
-                                             [nm = f t] ++ acc) []
-
-con mapUT = fn f :: Type => fold (fn nm t acc [[nm] ~ acc] =>
-                                     [nm = f] ++ acc) []
-
-con mapT2T = fn f :: (Type * Type) -> Type => fold (fn nm t acc [[nm] ~ acc] =>
-                                                       [nm = f t] ++ acc) []
-
-con mapT3T = fn f :: (Type * Type * Type) -> Type => fold (fn nm t acc [[nm] ~ acc] =>
-                                                              [nm = f t] ++ acc) []
+con mapUT = fn f :: Type => map (fn _ :: Unit => f)
 
 con ex = fn tf :: (Type -> Type) =>
             res ::: Type -> (choice :: Type -> tf choice -> res) -> res
@@ -53,19 +43,19 @@ val foldTR : tf :: (Type -> Type) -> tr :: ({Type} -> Type)
              -> (nm :: Name -> t :: Type -> rest :: {Type}
                  -> fn [[nm] ~ rest] =>
                        tf t -> tr rest -> tr ([nm = t] ++ rest))
-             -> tr [] -> r :: {Type} -> $(mapTT tf r) -> tr r
+             -> tr [] -> r :: {Type} -> $(map tf r) -> tr r
 
 val foldT2R : tf :: ((Type * Type) -> Type) -> tr :: ({(Type * Type)} -> Type)
               -> (nm :: Name -> t :: (Type * Type) -> rest :: {(Type * Type)}
                   -> fn [[nm] ~ rest] =>
                         tf t -> tr rest -> tr ([nm = t] ++ rest))
-              -> tr [] -> r :: {(Type * Type)} -> $(mapT2T tf r) -> tr r
+              -> tr [] -> r :: {(Type * Type)} -> $(map tf r) -> tr r
 
 val foldT3R : tf :: ((Type * Type * Type) -> Type) -> tr :: ({(Type * Type * Type)} -> Type)
               -> (nm :: Name -> t :: (Type * Type * Type) -> rest :: {(Type * Type * Type)}
                   -> fn [[nm] ~ rest] =>
                         tf t -> tr rest -> tr ([nm = t] ++ rest))
-              -> tr [] -> r :: {(Type * Type * Type)} -> $(mapT3T tf r) -> tr r
+              -> tr [] -> r :: {(Type * Type * Type)} -> $(map tf r) -> tr r
 
 val foldTR2 : tf1 :: (Type -> Type) -> tf2 :: (Type -> Type)
               -> tr :: ({Type} -> Type)
@@ -73,7 +63,7 @@ val foldTR2 : tf1 :: (Type -> Type) -> tf2 :: (Type -> Type)
                   -> fn [[nm] ~ rest] =>
                         tf1 t -> tf2 t -> tr rest -> tr ([nm = t] ++ rest))
               -> tr []
-              -> r :: {Type} -> $(mapTT tf1 r) -> $(mapTT tf2 r) -> tr r
+              -> r :: {Type} -> $(map tf1 r) -> $(map tf2 r) -> tr r
                                                                     
 val foldT2R2 : tf1 :: ((Type * Type) -> Type) -> tf2 :: ((Type * Type) -> Type)
                -> tr :: ({(Type * Type)} -> Type)
@@ -81,7 +71,7 @@ val foldT2R2 : tf1 :: ((Type * Type) -> Type) -> tf2 :: ((Type * Type) -> Type)
                    -> fn [[nm] ~ rest] =>
                          tf1 t -> tf2 t -> tr rest -> tr ([nm = t] ++ rest))
                -> tr [] -> r :: {(Type * Type)}
-               -> $(mapT2T tf1 r) -> $(mapT2T tf2 r) -> tr r
+               -> $(map tf1 r) -> $(map tf2 r) -> tr r
 
 val foldT3R2 : tf1 :: ((Type * Type * Type) -> Type) -> tf2 :: ((Type * Type * Type) -> Type)
                -> tr :: ({(Type * Type * Type)} -> Type)
@@ -89,32 +79,32 @@ val foldT3R2 : tf1 :: ((Type * Type * Type) -> Type) -> tf2 :: ((Type * Type * T
                    -> fn [[nm] ~ rest] =>
                          tf1 t -> tf2 t -> tr rest -> tr ([nm = t] ++ rest))
                -> tr [] -> r :: {(Type * Type * Type)}
-               -> $(mapT3T tf1 r) -> $(mapT3T tf2 r) -> tr r
+               -> $(map tf1 r) -> $(map tf2 r) -> tr r
 
 val foldTRX : tf :: (Type -> Type) -> ctx :: {Unit}
               -> (nm :: Name -> t :: Type -> rest :: {Type}
                   -> fn [[nm] ~ rest] =>
                         tf t -> xml ctx [] [])
-              -> r :: {Type} -> $(mapTT tf r) -> xml ctx [] []
+              -> r :: {Type} -> $(map tf r) -> xml ctx [] []
 
 val foldT2RX : tf :: ((Type * Type) -> Type) -> ctx :: {Unit}
                -> (nm :: Name -> t :: (Type * Type) -> rest :: {(Type * Type)}
                    -> fn [[nm] ~ rest] =>
                          tf t -> xml ctx [] [])
-               -> r :: {(Type * Type)} -> $(mapT2T tf r) -> xml ctx [] []
+               -> r :: {(Type * Type)} -> $(map tf r) -> xml ctx [] []
 
 val foldT3RX : tf :: ((Type * Type * Type) -> Type) -> ctx :: {Unit}
                -> (nm :: Name -> t :: (Type * Type * Type) -> rest :: {(Type * Type * Type)}
                    -> fn [[nm] ~ rest] =>
                          tf t -> xml ctx [] [])
-               -> r :: {(Type * Type * Type)} -> $(mapT3T tf r) -> xml ctx [] []
+               -> r :: {(Type * Type * Type)} -> $(map tf r) -> xml ctx [] []
 
 val foldTRX2 : tf1 :: (Type -> Type) -> tf2 :: (Type -> Type) -> ctx :: {Unit}
                -> (nm :: Name -> t :: Type -> rest :: {Type}
                    -> fn [[nm] ~ rest] =>
                          tf1 t -> tf2 t -> xml ctx [] [])
                -> r :: {Type}
-               -> $(mapTT tf1 r) -> $(mapTT tf2 r) -> xml ctx [] []
+               -> $(map tf1 r) -> $(map tf2 r) -> xml ctx [] []
 
 val foldT2RX2 : tf1 :: ((Type * Type) -> Type) -> tf2 :: ((Type * Type) -> Type)
                 -> ctx :: {Unit}
@@ -122,7 +112,7 @@ val foldT2RX2 : tf1 :: ((Type * Type) -> Type) -> tf2 :: ((Type * Type) -> Type)
                     -> fn [[nm] ~ rest] =>
                           tf1 t -> tf2 t -> xml ctx [] [])
                 -> r :: {(Type * Type)}
-                -> $(mapT2T tf1 r) -> $(mapT2T tf2 r) -> xml ctx [] []
+                -> $(map tf1 r) -> $(map tf2 r) -> xml ctx [] []
 
 
 val foldT3RX2 : tf1 :: ((Type * Type * Type) -> Type) -> tf2 :: ((Type * Type * Type) -> Type)
@@ -131,21 +121,19 @@ val foldT3RX2 : tf1 :: ((Type * Type * Type) -> Type) -> tf2 :: ((Type * Type *
                     -> fn [[nm] ~ rest] =>
                           tf1 t -> tf2 t -> xml ctx [] [])
                 -> r :: {(Type * Type * Type)}
-                -> $(mapT3T tf1 r) -> $(mapT3T tf2 r) -> xml ctx [] []
+                -> $(map tf1 r) -> $(map tf2 r) -> xml ctx [] []
 
 val queryX : tables ::: {{Type}} -> exps ::: {Type} -> ctx ::: {Unit}
              -> sql_query tables exps
              -> fn [tables ~ exps] =>
-                   ($(exps ++ fold (fn nm (fields :: {Type}) acc [[nm] ~ acc] =>
-                                       [nm = $fields] ++ acc) [] tables)
+                   ($(exps ++ map (fn fields :: {Type} => $fields) tables)
                     -> xml ctx [] [])
                    -> transaction (xml ctx [] [])
 
 val queryX' : tables ::: {{Type}} -> exps ::: {Type} -> ctx ::: {Unit}
               -> sql_query tables exps
               -> fn [tables ~ exps] =>
-                    ($(exps ++ fold (fn nm (fields :: {Type}) acc [[nm] ~ acc] =>
-                                        [nm = $fields] ++ acc) [] tables)
+                    ($(exps ++ map (fn fields :: {Type} => $fields) tables)
                      -> transaction (xml ctx [] []))
                     -> transaction (xml ctx [] [])
                        
@@ -155,20 +143,14 @@ val oneOrNoRows : tables ::: {{Type}} -> exps ::: {Type}
                         transaction
                             (option
                                  $(exps
-                                       ++ fold (fn nm (fields :: {Type}) acc
-                                                      [[nm] ~ acc] =>
-                                                   [nm = $fields] ++ acc)
-                                                   [] tables))
+                                       ++ map (fn fields :: {Type} => $fields) tables))
 
 val oneRow : tables ::: {{Type}} -> exps ::: {Type}
              -> sql_query tables exps
              -> fn [tables ~ exps] =>
                    transaction
                        $(exps
-                             ++ fold (fn nm (fields :: {Type}) acc
-                                            [[nm] ~ acc] =>
-                                         [nm = $fields] ++ acc)
-                                         [] tables)
+                             ++ map (fn fields :: {Type} => $fields) tables)
 
 val eqNullable : tables ::: {{Type}} -> agg ::: {{Type}} -> exps ::: {Type}
                  -> t ::: Type -> sql_injectable (option t)