constructors === id (#693)

dhall/src/Dhall/Core.hs

@@ -1897,14 +1897,8 @@ normalizeWithM ctx e0 = loop (denote e0)
     Constructors t   -> do
         t' <- loop t
         case t' of
-            Union kts -> pure (RecordLit kvs)
-              where
-                kvs = Dhall.Map.mapWithKey adapt kts
-
-                adapt k t_ = Lam k t_ (UnionLit k (Var (V k 0)) rest)
-                  where
-                    rest = Dhall.Map.delete k kts
-            _ -> pure (Constructors t')
+            u@(Union _) -> pure u
+            _           -> pure $ Constructors t'
     Field r x        -> do
         r' <- loop r
         case r' of

dhall/src/Dhall/TypeCheck.hs

@@ -771,13 +771,10 @@ typeWithA tpa = loop
     loop ctx e@(Constructors t  ) = do
         _ <- loop ctx t
 
-        kts <- case Dhall.Core.normalize t of
-            Union kts -> return kts
-            t'        -> Left (TypeError ctx e (ConstructorsRequiresAUnionType t t'))
+        case Dhall.Core.normalize t of
+            u@(Union _) -> loop ctx u
+            t'          -> Left (TypeError ctx e (ConstructorsRequiresAUnionType t t'))
 
-        let adapt k t_ = Pi k t_ (Union kts)
-
-        return (Record (Dhall.Map.mapWithKey adapt kts))
     loop ctx e@(Field r x       ) = do
         t <- fmap Dhall.Core.normalize (loop ctx r)
 

dhall/tests/import/success/issue553B.dhall

@@ -1 +1 @@
-./issue553A.dhall sha256:6fb582c043889dd5a4c97176f8a58d2633252b5374cb71e288b93bc3757f9643
+./issue553A.dhall sha256:e2d014696fb7d773727ae5aa42dc20bbd2447ea82bcb5971ccbb7763906edace

dhall/tests/tutorial/unions4B.dhall

@@ -1,6 +1 @@
-{ Empty  =
-    λ(Empty : {}) → < Empty = Empty | Person : { age : Natural, name : Text } >
-, Person =
-      λ(Person : { age : Natural, name : Text })
-    → < Person = Person | Empty : {} >
-}
+< Empty : {} | Person : { name : Text, age : Natural } >