Generalize grammar for certain annotation expressions (#2320)

… as standardized in dhall-lang/dhall-lang#1230

Author: Gabriella439

dhall/src/Dhall/Parser/Expression.hs

@@ -418,15 +418,15 @@ parsers embedded = Parsers{..}
                             nonemptyWhitespace
                             case (shallowDenote a, a0Info) of
                                 (ListLit Nothing [], _) -> do
-                                    b <- applicationExpression
+                                    b <- expression
 
                                     return (ListLit (Just b) [])
                                 (Merge c d Nothing, NakedMergeOrSomeOrToMap) -> do
-                                    b <- applicationExpression
+                                    b <- expression
 
                                     return (Merge c d (Just b))
                                 (ToMap c Nothing, NakedMergeOrSomeOrToMap) -> do
-                                    b <- applicationExpression
+                                    b <- expression
 
                                     return (ToMap c (Just b))
                                 _ -> do

dhall/src/Dhall/Pretty/Internal.hs

@@ -861,15 +861,15 @@ prettyPrinters characterSet =
                 <>  Pretty.indent 2 (prettyImportExpression_ b)
                 <>  Pretty.hardline
                 <>  colon <> space
-                <>  prettyApplicationExpression c
+                <>  prettyExpression c
                 )
 
         short = keyword "merge" <> space
             <>  prettyImportExpression_ a
             <>  " "
             <>  prettyImportExpression_ b
             <>  space <> colon <> space
-            <>  prettyApplicationExpression c
+            <>  prettyExpression c
     prettyAnnotatedExpression (ToMap a (Just b)) =
         Pretty.group (Pretty.flatAlt long short)
       where
@@ -880,13 +880,13 @@ prettyPrinters characterSet =
                 <>  Pretty.indent 2 (prettyImportExpression_ a)
                 <>  Pretty.hardline
                 <>  colon <> space
-                <>  prettyApplicationExpression b
+                <>  prettyExpression b
                 )
 
         short = keyword "toMap" <> space
             <>  prettyImportExpression_ a
             <>  space <> colon <> space
-            <>  prettyApplicationExpression b
+            <>  prettyExpression b
     prettyAnnotatedExpression a0@(Annot _ _) =
         enclose'
             ""
@@ -906,7 +906,7 @@ prettyPrinters characterSet =
     prettyAnnotatedExpression (ListLit (Just a) b) =
             list (map prettyExpression (Data.Foldable.toList b))
         <>  " : "
-        <>  prettyApplicationExpression a
+        <>  prettyExpression a
     prettyAnnotatedExpression a
         | Just doc <- preserveSource a =
             doc