Generalize empty list annotations

6 files changed, 37 insertions, 7 deletions

diff --git a/dhall-lang b/dhall-lang
-Subproject 1b587f866a16ce4ae198d5ff51848a4ffc0f4cd
+Subproject 4d68c5708cfc5c3f5ff7e5a6c4df25c5fdfd96f
diff --git a/dhall/build.rs b/dhall/build.rs
index 2d75cbf..07da3f5 100644
--- a/dhall/build.rs
+++ b/dhall/build.rs
@@ -103,6 +103,8 @@ fn main() -> std::io::Result<()> {
             || path == "success/unit/import/urls/potPourri"
             // TODO: toMap
             || path == "success/toMap"
+            // Not a failure anymore
+            || path == "failure/unit/ListLitEmptyPrecedence"
         },
     )?;
 
diff --git a/dhall/src/phase/binary.rs b/dhall/src/phase/binary.rs
index 66b235f..f88eee2 100644
--- a/dhall/src/phase/binary.rs
+++ b/dhall/src/phase/binary.rs
@@ -341,6 +341,10 @@ fn cbor_value_to_dhall(
                 let y = cbor_value_to_dhall(&y)?;
                 Annot(x, y)
             }
+            [U64(27), x] => {
+                let x = cbor_value_to_dhall(&x)?;
+                EmptyListLit(x)
+            }
             _ => Err(DecodeError::WrongFormatError(format!("{:?}", data)))?,
         },
         _ => Err(DecodeError::WrongFormatError(format!("{:?}", data)))?,
@@ -475,9 +479,9 @@ where
         EmptyListLit(x) => match x.as_ref() {
             App(f, a) => match f.as_ref() {
                 ExprF::Builtin(Builtin::List) => ser_seq!(ser; tag(4), expr(a)),
-                _ => unreachable!(),
+                _ => ser_seq!(ser; tag(27), expr(x)),
             },
-            _ => unreachable!(),
+            _ => ser_seq!(ser; tag(27), expr(x)),
         },
         NEListLit(xs) => ser.collect_seq(
             once(tag(4)).chain(once(null())).chain(xs.iter().map(expr)),
diff --git a/dhall_generated_parser/build.rs b/dhall_generated_parser/build.rs
index 1edce9e..7eba52c 100644
--- a/dhall_generated_parser/build.rs
+++ b/dhall_generated_parser/build.rs
@@ -31,6 +31,7 @@ fn main() -> std::io::Result<()> {
     rules.remove("simple_label");
     rules.remove("nonreserved_label");
     rules.remove("first_application_expression");
+    rules.remove("expression");
 
     let mut file = File::create(pest_path)?;
     writeln!(&mut file, "// AUTO-GENERATED FILE. See build.rs.")?;
@@ -65,6 +66,27 @@ fn main() -> std::io::Result<()> {
             | import_expression
     }}"
     )?;
+    // TODO: hack; we'll need to upstream a change to the grammar
+    writeln!(
+        &mut file,
+        r#"expression = {{
+          lambda ~ whsp ~ ^"(" ~ whsp ~ nonreserved_label ~ whsp ~ ^":" ~ whsp1 ~ expression ~ whsp ~ ^")" ~ whsp ~ arrow ~ whsp ~ expression
+          | if_ ~ whsp1 ~ expression ~ whsp ~ then ~ whsp1 ~ expression ~ whsp ~ else_ ~ whsp1 ~ expression
+          | let_binding+ ~ in_ ~ whsp1 ~ expression
+          | forall ~ whsp ~ ^"(" ~ whsp ~ nonreserved_label ~ whsp ~ ^":" ~ whsp1 ~ expression ~ whsp ~ ^")" ~ whsp ~ arrow ~ whsp ~ expression
+          | operator_expression ~ whsp ~ arrow ~ whsp ~ expression
+          | merge ~ whsp1 ~ import_expression ~ whsp1 ~ import_expression ~ whsp ~ ^":" ~ whsp1 ~ application_expression
+          | empty_list_literal
+          | toMap ~ whsp1 ~ import_expression ~ whsp ~ ^":" ~ whsp1 ~ application_expression
+          | annotated_expression
+    }}"#
+    )?;
+    writeln!(
+        &mut file,
+        r#"empty_list_literal = {{
+          ^"[" ~ whsp ~ ^"]" ~ whsp ~ ^":" ~ whsp1 ~ application_expression
+    }}"#
+    )?;
     // TODO: this is a cheat; properly support RFC3986 URLs instead
     writeln!(&mut file, "url_path = _{{ path }}")?;
     writeln!(
diff --git a/dhall_syntax/src/core/expr.rs b/dhall_syntax/src/core/expr.rs
index e33859b..14dc165 100644
--- a/dhall_syntax/src/core/expr.rs
+++ b/dhall_syntax/src/core/expr.rs
@@ -190,7 +190,7 @@ pub enum ExprF<SubExpr, Embed> {
     DoubleLit(Double),
     ///  `"Some ${interpolated} text"`
     TextLit(InterpolatedText<SubExpr>),
-    ///  `[] : List t`
+    ///  `[] : t`
     EmptyListLit(SubExpr),
     ///  `[x, y, z]`
     NEListLit(Vec<SubExpr>),
diff --git a/dhall_syntax/src/parser.rs b/dhall_syntax/src/parser.rs
index 0832af3..8a84b00 100644
--- a/dhall_syntax/src/parser.rs
+++ b/dhall_syntax/src/parser.rs
@@ -727,6 +727,12 @@ make_parser! {
     token_rule!(if_<()>);
     token_rule!(in_<()>);
 
+    rule!(empty_list_literal<ParsedSubExpr> as expression; span; children!(
+        [expression(e)] => {
+            spanned(span, EmptyListLit(e))
+        },
+    ));
+
     rule!(expression<ParsedSubExpr> as expression; span; children!(
         [lambda(()), label(l), expression(typ),
                 arrow(()), expression(body)] => {
@@ -751,10 +757,6 @@ make_parser! {
         [merge(()), expression(x), expression(y), expression(z)] => {
             spanned(span, Merge(x, y, Some(z)))
         },
-        [List(()), expression(x)] => {
-            let list = unspanned(Builtin(crate::Builtin::List));
-            spanned(span, EmptyListLit(unspanned(App(list, x))))
-        },
         [expression(e)] => e,
     ));