Merge pull request #171 from Nadrieril/catchup-spec

8 files changed, 68 insertions, 135 deletions

diff --git a/dhall/src/builtins.rs b/dhall/src/builtins.rs
index 67929a0..16d656f 100644
--- a/dhall/src/builtins.rs
+++ b/dhall/src/builtins.rs
@@ -42,8 +42,6 @@ pub enum Builtin {
     ListLast,
     ListIndexed,
     ListReverse,
-    OptionalFold,
-    OptionalBuild,
     TextShow,
 }
 
@@ -79,8 +77,6 @@ impl Builtin {
             "List/last" => Some(ListLast),
             "List/indexed" => Some(ListIndexed),
             "List/reverse" => Some(ListReverse),
-            "Optional/fold" => Some(OptionalFold),
-            "Optional/build" => Some(OptionalBuild),
             "Text/show" => Some(TextShow),
             _ => None,
         }
@@ -245,22 +241,6 @@ pub fn type_of_builtin(b: Builtin) -> Hir {
             forall (a: Type) -> (List a) -> List a
         ),
 
-        OptionalBuild => make_type!(
-            forall (a: Type) ->
-            (forall (optional: Type) ->
-                forall (just: a -> optional) ->
-                forall (nothing: optional) ->
-                optional) ->
-            Optional a
-        ),
-        OptionalFold => make_type!(
-            forall (a: Type) ->
-            (Optional a) ->
-            forall (optional: Type) ->
-            forall (just: a -> optional) ->
-            forall (nothing: optional) ->
-            optional
-        ),
         OptionalNone => make_type!(
             forall (A: Type) -> Optional A
         ),
@@ -510,27 +490,6 @@ fn apply_builtin(b: Builtin, args: Vec<Nir>, env: NzEnv) -> NirKind {
             }
             _ => Ret::DoneAsIs,
         },
-        (Builtin::OptionalBuild, [t, f]) => {
-            let optional_t =
-                Nir::from_builtin(Builtin::Optional).app(t.clone());
-            Ret::Nir(
-                f.app(optional_t)
-                    .app(
-                        make_closure(make_closure!(
-                            λ(T : Type) ->
-                            λ(a : var(T)) ->
-                            Some(var(a))
-                        ))
-                        .app(t.clone()),
-                    )
-                    .app(EmptyOptionalLit(t.clone()).into_nir()),
-            )
-        }
-        (Builtin::OptionalFold, [_, v, _, just, nothing]) => match &*v.kind() {
-            EmptyOptionalLit(_) => Ret::Nir(nothing.clone()),
-            NEOptionalLit(x) => Ret::Nir(just.app(x.clone())),
-            _ => Ret::DoneAsIs,
-        },
         (Builtin::NaturalBuild, [f]) => Ret::Nir(
             f.app(Nir::from_builtin(Builtin::Natural))
                 .app(make_closure(make_closure!(
@@ -600,8 +559,6 @@ impl std::fmt::Display for Builtin {
             ListLast => "List/last",
             ListIndexed => "List/indexed",
             ListReverse => "List/reverse",
-            OptionalFold => "Optional/fold",
-            OptionalBuild => "Optional/build",
             TextShow => "Text/show",
         })
     }
diff --git a/dhall/src/operations/kind.rs b/dhall/src/operations/kind.rs
index 5415637..0ee9671 100644
--- a/dhall/src/operations/kind.rs
+++ b/dhall/src/operations/kind.rs
@@ -6,6 +6,8 @@ use crate::syntax::{trivial_result, Label};
 // pretty-printing to work correctly
 #[derive(Debug, Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash)]
 pub enum BinOp {
+    /// x === y
+    Equivalence,
     /// `x ? y`
     ImportAlt,
     /// `x || y`
@@ -30,8 +32,6 @@ pub enum BinOp {
     BoolEQ,
     /// `x != y`
     BoolNE,
-    /// x === y
-    Equivalence,
 }
 
 /// Operations
diff --git a/dhall/src/semantics/tck/typecheck.rs b/dhall/src/semantics/tck/typecheck.rs
index 361e1b4..d21c7ce 100644
--- a/dhall/src/semantics/tck/typecheck.rs
+++ b/dhall/src/semantics/tck/typecheck.rs
@@ -137,30 +137,20 @@ fn type_one_layer(
             Type::from_const(k)
         }
         ExprKind::UnionType(kts) => {
-            // Check that all types are the same const
-            let mut k = None;
+            // An empty union type has type Type;
+            // an union type with only unary variants also has type Type
+            let mut k = Const::Type;
             for t in kts.values() {
                 if let Some(t) = t {
-                    let c = match t.ty().as_const() {
-                        Some(c) => c,
+                    match t.ty().as_const() {
+                        Some(c) => k = max(k, c),
                         None => {
                             return mk_span_err(t.span(), "InvalidVariantType")
                         }
-                    };
-                    match k {
-                        None => k = Some(c),
-                        Some(k) if k == c => {}
-                        _ => {
-                            return mk_span_err(t.span(), "InvalidVariantType")
-                        }
                     }
                 }
             }
 
-            // An empty union type has type Type;
-            // an union type with only unary variants also has type Type
-            let k = k.unwrap_or(Const::Type);
-
             Type::from_const(k)
         }
         ExprKind::Op(op) => typecheck_operation(env, span, op)?,
diff --git a/dhall/src/syntax/ast/span.rs b/dhall/src/syntax/ast/span.rs
index e250602..ab3279b 100644
--- a/dhall/src/syntax/ast/span.rs
+++ b/dhall/src/syntax/ast/span.rs
@@ -66,6 +66,12 @@ impl Span {
                     end: max(x.end, y.end),
                 })
             }
+            (Parsed(_), Parsed(_)) => panic!(
+                "Tried to union incompatible spans: {:?} and {:?}",
+                self, other
+            ),
+            (Parsed(x), _) => Parsed(x.clone()),
+            (_, Parsed(x)) => Parsed(x.clone()),
             _ => panic!(
                 "Tried to union incompatible spans: {:?} and {:?}",
                 self, other
diff --git a/dhall/src/syntax/text/dhall.abnf b/dhall/src/syntax/text/dhall.abnf
index 1c3a980..37ec43b 100644
--- a/dhall/src/syntax/text/dhall.abnf
+++ b/dhall/src/syntax/text/dhall.abnf
@@ -206,7 +206,7 @@ quoted-label-char =
         ; %x60 = '`'

     / %x61-7E

 

-quoted-label = 1*quoted-label-char

+quoted-label = *quoted-label-char

 

 ; NOTE: Dhall does not support Unicode labels, mainly to minimize the potential

 ; for code obfuscation

@@ -370,7 +370,9 @@ NaN                   = %x4e.61.4e
 Some                  = %x53.6f.6d.65

 toMap                 = %x74.6f.4d.61.70

 assert                = %x61.73.73.65.72.74

-forall                = %x2200 / %x66.6f.72.61.6c.6c ; "∀" / "forall"

+forall-keyword        = %x66.6f.72.61.6c.6c ; "forall"

+forall-symbol         = %x2200 ; Unicode FOR ALL

+forall                = forall-symbol / forall-keyword

 with                  = %x77.69.74.68

 

 ; Unused rule that could be used as negative lookahead in the

@@ -382,9 +384,12 @@ keyword =
     / assert / as

     / Infinity / NaN

     / merge / Some / toMap

-    / forall

+    / forall-keyword

     / with

 

+; Note that there is a corresponding parser test in

+; `tests/parser/success/builtinsA.dhall`. Please update it when

+; you modify this `builtin` rule.

 builtin =

       Natural-fold

     / Natural-build

@@ -406,8 +411,6 @@ builtin =
     / List-last

     / List-indexed

     / List-reverse

-    / Optional-fold

-    / Optional-build

     / Text-show

     / Bool

     / True

@@ -460,8 +463,6 @@ List-head         = %x4c.69.73.74.2f.68.65.61.64
 List-last         = %x4c.69.73.74.2f.6c.61.73.74

 List-indexed      = %x4c.69.73.74.2f.69.6e.64.65.78.65.64

 List-reverse      = %x4c.69.73.74.2f.72.65.76.65.72.73.65

-Optional-fold     = %x4f.70.74.69.6f.6e.61.6c.2f.66.6f.6c.64

-Optional-build    = %x4f.70.74.69.6f.6e.61.6c.2f.62.75.69.6c.64

 Text-show         = %x54.65.78.74.2f.73.68.6f.77

 

 ; Operators

@@ -580,7 +581,6 @@ scheme = %x68.74.74.70 [ %x73 ]  ; "http" [ "s" ]
 

 ; NOTE: This does not match the official grammar for a URI.  Specifically:

 ;

-; * path segments may be quoted instead of using percent-encoding

 ; * this does not support fragment identifiers, which have no meaning within

 ;   Dhall expressions and do not affect import resolution

 ; * the characters "(" ")" and "," are not included in the `sub-delims` rule:

@@ -593,13 +593,9 @@ scheme = %x68.74.74.70 [ %x73 ]  ; "http" [ "s" ]
 ;

 ; Reserved characters in quoted path components should be percent-encoded

 ; according to https://tools.ietf.org/html/rfc3986#section-2

-http-raw = scheme "://" authority url-path [ "?" query ]

+http-raw = scheme "://" authority path-abempty [ "?" query ]

 

-; Temporary rule to allow old-style `path-component`s and RFC3986 `segment`s in

-; the same grammar. Eventually we can just use `path-abempty` from the same

-; RFC. See issue #581

-

-url-path = *(path-component / "/" segment)

+path-abempty = *( "/" segment )

 

 ; NOTE: Backtrack if parsing the optional user info prefix fails

 authority = [ userinfo "@" ] host [ ":" port ]

@@ -757,6 +753,11 @@ expression =
     ; NOTE: Backtrack if parsing this alternative fails

     / operator-expression whsp arrow whsp expression

     

+    ; "a with x = b"

+    ;

+    ; NOTE: Backtrack if parsing this alternative fails

+    / with-expression

+    

     ; "merge e1 e2 : t"

     ;

     ; NOTE: Backtrack if parsing this alternative fails since we can't tell

@@ -792,9 +793,16 @@ let-binding = let whsp1 nonreserved-label whsp [ ":" whsp1 expression whsp ] "="
 empty-list-literal =

     "[" whsp [ "," whsp ] "]" whsp ":" whsp1 application-expression

 

-operator-expression = import-alt-expression

+with-expression =

+    import-expression 1*(whsp1 with whsp1 with-clause)

+

+with-clause =

+    any-label-or-some *(whsp "." whsp any-label-or-some) whsp "=" whsp operator-expression

+

+operator-expression = equivalent-expression

 

 ; Nonempty-whitespace to disambiguate `http://a/a?a`

+equivalent-expression    = import-alt-expression    *(whsp equivalent whsp import-alt-expression)

 import-alt-expression    = or-expression            *(whsp "?" whsp1 or-expression)

 or-expression            = plus-expression          *(whsp "||" whsp plus-expression)

 ; Nonempty-whitespace to disambiguate `f +2`

@@ -807,13 +815,7 @@ prefer-expression        = combine-types-expression *(whsp prefer whsp combine-t
 combine-types-expression = times-expression         *(whsp combine-types whsp times-expression)

 times-expression         = equal-expression         *(whsp "*" whsp equal-expression)

 equal-expression         = not-equal-expression     *(whsp "==" whsp not-equal-expression)

-not-equal-expression     = equivalent-expression    *(whsp "!=" whsp equivalent-expression)

-equivalent-expression    = with-expression          *(whsp equivalent whsp with-expression)

-

-with-expression = application-expression *(whsp1 with whsp1 with-clause)

-

-with-clause =

-    any-label-or-some *(whsp "." whsp any-label-or-some) whsp "=" whsp application-expression

+not-equal-expression     = application-expression   *(whsp "!=" whsp application-expression)

 

 

 ; Import expressions need to be separated by some whitespace, otherwise there

@@ -890,11 +892,9 @@ primitive-expression =
 

 record-type-or-literal =

       empty-record-literal

-    / non-empty-record-type-or-literal

-    / empty-record-type

+    / [non-empty-record-type-or-literal]

 

 empty-record-literal = "="

-empty-record-type = ""

 

 non-empty-record-type-or-literal =

     (non-empty-record-type / non-empty-record-literal)

@@ -907,22 +907,18 @@ record-type-entry = any-label-or-some whsp ":" whsp1 expression
 non-empty-record-literal =

     record-literal-entry *(whsp "," whsp record-literal-entry)

 

+; If the `record-literal-normal-entry` is absent, that represents a punned

+; record entry, such as in `{ x }`, which is a short-hand for `{ x = x }`

 record-literal-entry =

-    any-label-or-some (record-literal-normal-entry / record-literal-punned-entry)

+    any-label-or-some [record-literal-normal-entry]

 

 record-literal-normal-entry =

     *(whsp "." whsp any-label-or-some) whsp "=" whsp expression

-record-literal-punned-entry = ""

-

 

+; If the `union-type-entry` is absent, that represents an empty union

+; alternative, such as in `< Heads | Tails >`

 union-type =

-      non-empty-union-type

-    / empty-union-type

-

-empty-union-type = ""

-

-non-empty-union-type =

-    union-type-entry *(whsp "|" whsp union-type-entry)

+    [union-type-entry *(whsp "|" whsp union-type-entry)]

 

 ; x : Natural

 ; x

diff --git a/dhall/src/syntax/text/dhall.pest.visibility b/dhall/src/syntax/text/dhall.pest.visibility
index b2114ce..6de7dd2 100644
--- a/dhall/src/syntax/text/dhall.pest.visibility
+++ b/dhall/src/syntax/text/dhall.pest.visibility
@@ -120,7 +120,7 @@ home_path
 absolute_path
 scheme
 http_raw
-url_path
+path_abempty
 authority
 # userinfo
 # host
@@ -178,19 +178,15 @@ selector
 labels
 # type_selector
 primitive_expression
-# record_type_or_literal
+record_type_or_literal
 empty_record_literal
-empty_record_type
-non_empty_record_type_or_literal
+# non_empty_record_type_or_literal
 non_empty_record_type
 record_type_entry
 non_empty_record_literal
 record_literal_entry
-# record_literal_punned_entry
 # record_literal_normal_entry
 union_type
-empty_union_type
-# non_empty_union_type
 union_type_entry
 non_empty_list_literal
 # complete_expression
diff --git a/dhall/src/syntax/text/parser.rs b/dhall/src/syntax/text/parser.rs
index 1e1449c..06c1ac3 100644
--- a/dhall/src/syntax/text/parser.rs
+++ b/dhall/src/syntax/text/parser.rs
@@ -130,6 +130,7 @@ lazy_static::lazy_static! {
         use Rule::*;
         // In order of precedence
         let operators = vec![
+            equivalent,
             import_alt,
             bool_or,
             natural_plus,
@@ -142,7 +143,6 @@ lazy_static::lazy_static! {
             natural_times,
             bool_eq,
             bool_ne,
-            equivalent,
         ];
         PrecClimber::new(
             operators
@@ -514,14 +514,14 @@ impl DhallParser {
 
     fn http_raw(input: ParseInput) -> ParseResult<URL<Expr>> {
         Ok(match_nodes!(input.into_children();
-            [scheme(sch), authority(auth), url_path(p)] => URL {
+            [scheme(sch), authority(auth), path_abempty(p)] => URL {
                 scheme: sch,
                 authority: auth,
                 path: p,
                 query: None,
                 headers: None,
             },
-            [scheme(sch), authority(auth), url_path(p), query(q)] => URL {
+            [scheme(sch), authority(auth), path_abempty(p), query(q)] => URL {
                 scheme: sch,
                 authority: auth,
                 path: p,
@@ -531,10 +531,10 @@ impl DhallParser {
         ))
     }
 
-    fn url_path(input: ParseInput) -> ParseResult<FilePath> {
+    fn path_abempty(input: ParseInput) -> ParseResult<FilePath> {
         Ok(match_nodes!(input.into_children();
-            [path_component(components)..] => {
-                let mut file_path: Vec<_> = components.collect();
+            [segment(segments)..] => {
+                let mut file_path: Vec<_> = segments.collect();
                 // An empty path normalizes to "/"
                 if file_path.is_empty() {
                     file_path = vec!["".to_owned()];
@@ -548,7 +548,6 @@ impl DhallParser {
         Ok(input.as_str().to_owned())
     }
 
-    #[alias(path_component)]
     fn segment(input: ParseInput) -> ParseResult<String> {
         Ok(input.as_str().to_string())
     }
@@ -909,26 +908,19 @@ impl DhallParser {
         ))
     }
 
-    #[alias(record_type_or_literal)]
-    fn empty_record_literal(input: ParseInput) -> ParseResult<UnspannedExpr> {
-        Ok(RecordLit(Default::default()))
-    }
-
-    #[alias(record_type_or_literal)]
-    fn empty_record_type(input: ParseInput) -> ParseResult<UnspannedExpr> {
-        Ok(RecordType(Default::default()))
-    }
-
-    #[alias(record_type_or_literal)]
-    fn non_empty_record_type_or_literal(
-        input: ParseInput,
-    ) -> ParseResult<UnspannedExpr> {
+    fn record_type_or_literal(input: ParseInput) -> ParseResult<UnspannedExpr> {
         Ok(match_nodes!(input.children();
+            [empty_record_literal(_)] => RecordLit(Default::default()),
             [non_empty_record_type(map)] => RecordType(map),
             [non_empty_record_literal(map)] => RecordLit(map),
+            [] => RecordType(Default::default()),
         ))
     }
 
+    fn empty_record_literal(input: ParseInput) -> ParseResult<()> {
+        Ok(())
+    }
+
     fn non_empty_record_type(
         input: ParseInput,
     ) -> ParseResult<BTreeMap<Label, Expr>> {
@@ -997,8 +989,7 @@ impl DhallParser {
     }
 
     fn union_type(input: ParseInput) -> ParseResult<UnspannedExpr> {
-        let map = match_nodes!(input.children();
-            [empty_union_type(_)] => Default::default(),
+        Ok(match_nodes!(input.children();
             [union_type_entry(entries)..] => {
                 let mut map = BTreeMap::default();
                 for (l, t) in entries {
@@ -1015,14 +1006,9 @@ impl DhallParser {
                         }
                     }
                 }
-                map
+                UnionType(map)
             },
-        );
-        Ok(UnionType(map))
-    }
-
-    fn empty_union_type(_input: ParseInput) -> ParseResult<()> {
-        Ok(())
+        ))
     }
 
     fn union_type_entry(
@@ -1065,7 +1051,7 @@ pub fn parse_expr(input_str: &str) -> ParseResult<Expr> {
 }
 
 #[test]
-#[ignore]
+#[cfg_attr(windows, ignore)]
 // Check that the local copy of the grammar file is in sync with the one from dhall-lang.
 fn test_grammar_files_in_sync() {
     use std::process::Command;
@@ -1079,8 +1065,8 @@ fn test_grammar_files_in_sync() {
         .arg("--ignore-space-change")
         .arg("--color")
         .arg("--")
-        .arg(spec_abnf_path)
         .arg(local_abnf_path)
+        .arg(spec_abnf_path)
         .output()
         .expect("failed to run `git diff` command");
 
diff --git a/dhall/src/syntax/text/printer.rs b/dhall/src/syntax/text/printer.rs
index ccba385..8815d69 100644
--- a/dhall/src/syntax/text/printer.rs
+++ b/dhall/src/syntax/text/printer.rs
@@ -154,7 +154,9 @@ fn fmt_label(label: &Label, f: &mut fmt::Formatter) -> Result<(), fmt::Error> {
         | "True" | "False" | "Some" => true,
         _ => Builtin::parse(&s).is_some(),
     };
-    if !is_reserved && s.chars().all(|c| c.is_ascii_alphanumeric()) {
+    if s.is_empty() {
+        write!(f, "``")
+    } else if !is_reserved && s.chars().all(|c| c.is_ascii_alphanumeric()) {
         write!(f, "{}", s)
     } else {
         write!(f, "`{}`", s)