Merge branch 'master' into exprf

3 files changed, 199 insertions, 220 deletions

diff --git a/dhall_parser/build.rs b/dhall_parser/build.rs
index 4e75181..615a55c 100644
--- a/dhall_parser/build.rs
+++ b/dhall_parser/build.rs
@@ -42,13 +42,6 @@ fn main() -> std::io::Result<()> {
     )?;
     writeln!(
         &mut file,
-        "keyword = _{{
-            let_ | in_ | if_ | then
-                | else_ | Infinity | NaN
-    }}"
-    )?;
-    writeln!(
-        &mut file,
         "final_expression = ${{ SOI ~ complete_expression ~ EOI }}"
     )?;
 
diff --git a/dhall_parser/src/dhall.abnf b/dhall_parser/src/dhall.abnf
index 02edc84..847da02 100644
--- a/dhall_parser/src/dhall.abnf
+++ b/dhall_parser/src/dhall.abnf
@@ -100,10 +100,9 @@
 ;

 ; For simplicity this supports Unix and Windows line-endings, which are the most

 ; common

-end-of-line-silent =

+end-of-line =

       %x0A     ; "\n"

     / %x0D.0A  ; "\r\n"

-end-of-line = end-of-line-silent

 

 tab = %x09  ; "\t"

 

@@ -113,7 +112,7 @@ block-comment-chunk =
       block-comment

     / %x20-10FFFF

     / tab

-    / end-of-line-silent

+    / end-of-line

 

 block-comment-continue = "-}" / block-comment-chunk block-comment-continue

 

@@ -121,18 +120,19 @@ not-end-of-line = %x20-10FFFF / tab
 

 ; NOTE: Slightly different from Haskell-style single-line comments because this

 ; does not require a space after the dashes

-line-comment = "--" *not-end-of-line end-of-line-silent

+line-comment = "--" *not-end-of-line end-of-line

 

 whitespace-chunk =

       " "

     / tab

-    / end-of-line-silent

+    / end-of-line

     / line-comment

     / block-comment

 

-whitespace = *whitespace-chunk

+whsp = *whitespace-chunk

 

-nonempty-whitespace = 1*whitespace-chunk

+; nonempty whitespace

+whsp1 = 1*whitespace-chunk

 

 ; Uppercase or lowercase ASCII letter

 ALPHA = %x41-5A / %x61-7A

@@ -142,19 +142,13 @@ DIGIT = %x30-39  ; 0-9
 

 HEXDIG = DIGIT / "A" / "B" / "C" / "D" / "E" / "F"

 

-; A simple label cannot be one of the following reserved keywords:

-;

-; * if

-; * then

-; * else

-; * let

-; * in

-; * as

-; * using

-; * merge

-; * missing

-; * Infinity

-; * Some

+; A simple label cannot be one of the reserved keywords

+; listed in the `keyword` rule.

+; A PEG parser could use negative lookahead to

+; enforce this, e.g. as follows:

+; simple-label =

+;       keyword 1*simple-label-next-char

+;     / !keyword (simple-label-first-char *simple-label-next-char)

 simple-label-first-char = ALPHA / "_"

 simple-label-next-char = ALPHA / DIGIT / "-" / "/" / "_"

 simple-label = simple-label-first-char *simple-label-next-char

@@ -170,11 +164,12 @@ quoted-label = 1*quoted-label-char
 ; for code obfuscation

 label = ("`" quoted-label "`" / simple-label)

 

-; An unreserved-label cannot not be any of the reserved identifiers for builtins (unless quoted).

+; A nonreserved-label cannot not be any of the reserved identifiers for builtins (unless quoted).

 ; Their list can be found in semantics.md. This is not enforced by the grammar but

 ; should be checked by implementations. The only place where this restriction applies

 ; is bound variables.

-unreserved-label = label

+; A PEG parser could use negative lookahead to avoid parsing those identifiers.

+nonreserved-label = label

 

 ; An any-label is allowed to be one of the reserved identifiers.

 any-label = label

@@ -216,8 +211,8 @@ any-label = label
 ; > "\uD834\uDD1E".

 double-quote-chunk =

       interpolation

-      ; '\'

-    / %x5C double-quote-escaped 

+      ; '\'    Beginning of escape sequence

+    / %x5C double-quote-escaped

     / double-quote-char

 

 double-quote-escaped =

@@ -273,7 +268,6 @@ single-quote-char =
 

 single-quote-literal = "''" end-of-line single-quote-continue

 

-; Interpolation

 interpolation = "${" complete-expression "}"

 

 text-literal = (double-quote-literal / single-quote-literal)

@@ -281,25 +275,34 @@ text-literal = (double-quote-literal / single-quote-literal)
 ; RFC 5234 interprets string literals as case-insensitive and recommends using

 ; hex instead for case-sensitive strings

 ;

-; If you don't feel like reading hex, these are all the same as the rule name,

-; except without the '' ending.

+; If you don't feel like reading hex, these are all the same as the rule name.

 ; Keywords that should never be parsed as identifiers

-if                = %x69.66

-then              = %x74.68.65.6e

-else              = %x65.6c.73.65

-let               = %x6c.65.74

-in                = %x69.6e

-as                = %x61.73

-using             = %x75.73.69.6e.67

-merge             = %x6d.65.72.67.65

-missing           = %x6d.69.73.73.69.6e.67

-Infinity          = %x49.6e.66.69.6e.69.74.79

+if                    = %x69.66

+then                  = %x74.68.65.6e

+else                  = %x65.6c.73.65

+let                   = %x6c.65.74

+in                    = %x69.6e

+as                    = %x61.73

+using                 = %x75.73.69.6e.67

+merge                 = %x6d.65.72.67.65

+missing               = %x6d.69.73.73.69.6e.67

+Infinity              = %x49.6e.66.69.6e.69.74.79

+NaN                   = %x4e.61.4e

+Some                  = %x53.6f.6d.65

+

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

+; `simple-label` rule for parsers that support this.

+keyword =

+      if / then / else

+    / let / in

+    / using / missing / as

+    / Infinity / NaN

+    / merge / Some

+

 ; Reserved identifiers, only needed for some special cases of parsing

 Optional              = %x4f.70.74.69.6f.6e.61.6c

 Text                  = %x54.65.78.74

 List                  = %x4c.69.73.74

-NaN               = %x4e.61.4e

-Some              = %x53.6f.6d.65

 

 combine       = %x2227 / "/\"

 combine-types = %x2A53 / "//\\"

@@ -310,7 +313,20 @@ arrow         = %x2192 / "->"
 

 exponent = "e" [ "+" / "-" ] 1*DIGIT

 

-double-literal = [ "+" / "-" ] 1*DIGIT ( "." 1*DIGIT [ exponent ] / exponent)

+numeric-double-literal = [ "+" / "-" ] 1*DIGIT ( "." 1*DIGIT [ exponent ] / exponent)

+

+minus-infinity-literal = "-" Infinity

+plus-infinity-literal = Infinity

+

+double-literal =

+    ; "2.0"

+      numeric-double-literal

+    ; "-Infinity"

+    / minus-infinity-literal

+    ; "Infinity"

+    / plus-infinity-literal

+    ; "NaN"

+    / NaN

 

 natural-literal = 1*DIGIT

 

@@ -318,7 +334,7 @@ integer-literal = ( "+" / "-" ) natural-literal
 

 ; The implementation should recognize reserved names for builtins and treat them as special

 ; values instead of variables.

-identifier = any-label [ whitespace "@" whitespace natural-literal ]

+identifier = any-label [ whsp "@" whsp natural-literal ]

 

 ; Printable characters other than " ()[]{}<>/\,"

 ;

@@ -363,6 +379,8 @@ quoted-path-component = 1*quoted-path-character
 

 path-component = "/" ( unquoted-path-component / %x22 quoted-path-component %x22 )

 

+; The last path-component matched by this rule is referred to as "file" in the semantics,

+; and the other path-components as "directory".

 path = 1*path-component

 

 local =

@@ -445,7 +463,7 @@ sub-delims = "!" / "$" / "&" / "'" / "(" / ")" / "*" / "+" / "," / ";" / "="
 

 http =

     http-raw

-    [ whitespace using nonempty-whitespace (import-hashed / "(" whitespace import-hashed whitespace ")") ]

+    [ whsp using whsp1 (import-hashed / "(" whsp import-hashed whsp ")") ]

 

 ; Dhall supports unquoted environment variables that are Bash-compliant or

 ; quoted environment variables that are POSIX-compliant

@@ -513,117 +531,106 @@ posix-environment-variable-character =
 

 import-type = missing / local / http / env

 

-hash = %x73.68.61.32.35.36.3a 64HEXDIG  ; "sha256:XXX...XXX"

+hash = %x73.68.61.32.35.36.3a 64HEXDIG ; "sha256:XXX...XXX"

 

-import-hashed = import-type [ whitespace hash ]

+import-hashed = import-type [ whsp hash ]

 

 ; "http://example.com"

 ; "./foo/bar"

 ; "env:FOO"

-import = import-hashed [ whitespace as nonempty-whitespace Text ]

-

-; NOTE: Every rule past this point should only reference rules that end with

-; whitespace.  This ensures consistent handling of whitespace in the absence of

-; a separate lexing step.

-; The exception is the rules ending in , which should _not_ end in whitespace.

-; This is important to avoid the need for sequential backtracking in application-expression.

+import = import-hashed [ whsp as whsp1 Text ]

 

 expression =

-    lambda-expression

-    / ifthenelse-expression

-    / let-expression

-    / forall-expression

+    ; "\(x : a) -> b"

+      lambda whsp "(" whsp nonreserved-label whsp ":" whsp1 expression whsp ")" whsp arrow whsp expression

+    

+    ; "if a then b else c"

+    / if whsp1 expression whsp then whsp1 expression whsp else whsp1 expression

+    

+    ; "let x : t = e1 in e2"

+    ; "let x     = e1 in e2"

+    ; "let x = e1 let y = e2 in e3"

+    / 1*let-binding in whsp1 expression

+    

+    ; "forall (x : a) -> b"

+    / forall whsp "(" whsp nonreserved-label whsp ":" whsp1 expression whsp ")" whsp arrow whsp expression

+    

+    ; "a -> b"

+    ;

     ; NOTE: Backtrack if parsing this alternative fails

-    / arrow-expression

-    / merge-expression

+    / operator-expression whsp arrow whsp expression

+    

+    ; "merge e1 e2 : t"

+    ; "merge e1 e2"

+    / merge whsp1 import-expression whsp import-expression [ whsp ":" whsp1 application-expression ]

+    

+    ; "[]  : List     t"

+    ; "[]  : Optional t"

+    ; "[x] : Optional t"

+    ;

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

     ; from the opening bracket whether or not this will be an empty list or

     ; a non-empty list

-    / empty-list-or-optional

+    / "[" whsp (empty-collection / non-empty-optional)

+    

+    ; "x : t"

     / annotated-expression

 

-; "\(x : a) -> b"

-lambda-expression = lambda whitespace "(" whitespace unreserved-label whitespace ":" nonempty-whitespace expression ")" whitespace arrow whitespace expression

-

-; "if a then b else c"

-ifthenelse-expression = if nonempty-whitespace expression then nonempty-whitespace expression else nonempty-whitespace expression

-

-; "let x : t = e1 in e2"

-; "let x     = e1 in e2"

-; "let x = e1 let y = e2 in e3"

-let-expression = 1*let-binding in nonempty-whitespace expression

-let-binding = let nonempty-whitespace unreserved-label whitespace [ ":" nonempty-whitespace expression ] "=" whitespace expression

-

-; "forall (x : a) -> b"

-forall-expression = forall whitespace "(" whitespace unreserved-label whitespace ":" nonempty-whitespace expression ")" whitespace arrow whitespace expression

+; Nonempty-whitespace to disambiguate `env:VARIABLE` from type annotations

+annotated-expression = operator-expression [ whsp ":" whsp1 expression ]

 

-; "a -> b"

-arrow-expression = operator-expression arrow whitespace expression

+; "let x = e1"

+let-binding = let whsp1 nonreserved-label whsp [ ":" whsp1 expression whsp ] "=" whsp expression whsp

 

-; "merge e1 e2 : t"

-; "merge e1 e2"

-merge-expression = merge nonempty-whitespace import-expression whitespace import-expression whitespace [ ":" nonempty-whitespace application-expression ]

-

-; "[]  : List     t"

-; "[]  : Optional t"

-; "[x] : Optional t"

-empty-list-or-optional = "[" whitespace (empty-collection / non-empty-optional)

-empty-collection = "]" whitespace ":" nonempty-whitespace (List whitespace / Optional whitespace) import-expression whitespace

-non-empty-optional = expression "]" whitespace ":" nonempty-whitespace Optional whitespace import-expression whitespace

-

-; "x : t"

-annotated-expression = operator-expression [ ":" nonempty-whitespace expression ]

+; "]  : List     t"

+; "]  : Optional t"

+empty-collection = "]" whsp ":" whsp1 (List / Optional) whsp import-expression

 

+; "x] : Optional t"

+non-empty-optional = expression whsp "]" whsp ":" whsp1 Optional whsp import-expression

 

 operator-expression = import-alt-expression

 

-import-alt-expression    = or-expression            *("?" nonempty-whitespace    or-expression)

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

-plus-expression          = text-append-expression   *("+" nonempty-whitespace          text-append-expression  )

-text-append-expression   = list-append-expression   *("++" whitespace   list-append-expression  )

-list-append-expression   = and-expression           *("#" whitespace   and-expression          )

-and-expression           = combine-expression       *("&&" whitespace           combine-expression      )

-combine-expression       = prefer-expression        *(combine whitespace       prefer-expression       )

-prefer-expression        = combine-types-expression *(prefer whitespace        combine-types-expression)

-combine-types-expression = times-expression         *(combine-types whitespace times-expression        )

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

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

-not-equal-expression     = application-expression   *("!=" whitespace     application-expression  )

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

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

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

+; Nonempty-whitespace to disambiguate `f +2`

+plus-expression          = text-append-expression   *(whsp "+" whsp1 text-append-expression)

+text-append-expression   = list-append-expression   *(whsp "++" whsp list-append-expression)

+list-append-expression   = and-expression           *(whsp "#" whsp and-expression)

+and-expression           = combine-expression       *(whsp "&&" whsp combine-expression)

+combine-expression       = prefer-expression        *(whsp combine whsp prefer-expression)

+prefer-expression        = combine-types-expression *(whsp prefer whsp combine-types-expression)

+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     = application-expression   *(whsp "!=" whsp application-expression)

 

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

 ; would be ambiguity: `./ab` could be interpreted as "import the file `./ab`",

 ; or "apply the import `./a` to label `b`"

 application-expression =

-    import-expression *(nonempty-whitespace import-expression) whitespace

+    [ Some whsp1 ] import-expression *(whsp1 import-expression)

 

-import-expression =

-      import

-    / selector-expression

+import-expression = import / selector-expression

 

 ; `record.field` extracts one field of a record

+;

 ; `record.{ field0, field1, field2 }` projects out several fields of a record

 ;

-; NOTE: Backtrack when parsing the `*(dot ...)`.  The reason why is that you

+; NOTE: Backtrack when parsing the `*("." ...)`.  The reason why is that you

 ; can't tell from parsing just the period whether "foo." will become "foo.bar"

 ; (i.e. accessing field `bar` of the record `foo`) or `foo./bar` (i.e. applying

 ; the function `foo` to the relative path `./bar`)

-selector-expression = primitive-expression *(whitespace "." whitespace selector)

+selector-expression = primitive-expression *(whsp "." whsp selector)

 

 selector = any-label / labels

 

-labels = "{" whitespace [ any-label whitespace *("," whitespace any-label whitespace) ] "}"

-

-

-primitive-expression =

-      literal-expression

-    / "{" whitespace record-type-or-literal "}"

-    / "<" whitespace union-type-or-literal ">"

-    / non-empty-list-literal

-    / parenthesized-expression

+labels = "{" whsp [ any-label whsp *("," whsp any-label whsp) ] "}"

 

 ; NOTE: Backtrack when parsing the first three alternatives (i.e. the numeric

 ; literals).  This is because they share leading characters in common

-literal-expression =

+primitive-expression =

     ; "2.0"

       double-literal

     

@@ -633,60 +640,65 @@ literal-expression =
     ; "+2"

     / integer-literal

     

-    ; "-Infinity"

-    / minus-infinity-literal

-    ; "Infinity"

-    / plus-infinity-literal

-    ; "NaN"

-    / NaN

-    

     ; '"ABC"'

     / text-literal

     

+    ; "{ foo = 1      , bar = True }"

+    ; "{ foo : Integer, bar : Bool }"

+    / "{" whsp record-type-or-literal whsp "}"

+    

+    ; "< Foo : Integer | Bar : Bool >"

+    ; "< Foo : Integer | Bar = True | Baz : Bool >"

+    ; "< Foo | Bar : Bool >"

+    / "<" whsp union-type-or-literal whsp ">"

+    

+    ; "[1, 2, 3]"

+    ; `empty-collection` handles empty lists

+    / non-empty-list-literal

+    

     ; "x"

     ; "x@2"

     / identifier

+    

+    ; "( e )"

+    / "(" complete-expression ")"

 

-minus-infinity-literal = "-" Infinity

-plus-infinity-literal = Infinity

-

-; "{ foo = 1      , bar = True }"

-; "{ foo : Integer, bar : Bool }"

 record-type-or-literal =

       empty-record-literal

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

     / empty-record-type

-empty-record-literal = "=" whitespace

+

+empty-record-literal = "="

 empty-record-type = ""

+

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

-    any-label whitespace (non-empty-record-literal / non-empty-record-type)

-non-empty-record-type    = ":" nonempty-whitespace expression *("," whitespace record-type-entry)

-record-type-entry = any-label whitespace ":" nonempty-whitespace expression

-non-empty-record-literal = "=" whitespace expression *("," whitespace record-literal-entry)

-record-literal-entry = any-label whitespace "=" whitespace expression

-

-; "< Foo : Integer | Bar : Bool >"

-; "< Foo : Integer | Bar = True >"

+    any-label whsp (non-empty-record-literal / non-empty-record-type)

+

+non-empty-record-type = ":" whsp1 expression *(whsp "," whsp record-type-entry)

+record-type-entry = any-label whsp ":" whsp1 expression

+

+non-empty-record-literal = "=" whsp expression *(whsp "," whsp record-literal-entry)

+record-literal-entry = any-label whsp "=" whsp expression

+

 union-type-or-literal =

       non-empty-union-type-or-literal

     / empty-union-type

+

 empty-union-type = ""

+

 non-empty-union-type-or-literal =

-    any-label whitespace

-    ( "=" whitespace expression union-type-entries

-    / ":" nonempty-whitespace expression [ "|" whitespace non-empty-union-type-or-literal ]

-    )

-union-type-entries = *("|" whitespace union-type-entry)

-union-type-entry = any-label whitespace ":" nonempty-whitespace expression

+    any-label [ whsp ( union-literal-variant-value / union-type-or-literal-variant-type) ]

+

+; = True | ...

+union-literal-variant-value = "=" whsp expression *(whsp "|" whsp union-type-entry)

+union-type-entry = any-label whsp ":" whsp1 expression

 

-; "[1, 2, 3]"

-; `empty-list-or-optional` handles empty lists

-non-empty-list-literal = "[" whitespace expression *("," whitespace expression) "]"

+; : Integer | ...

+; | ...

+union-type-or-literal-variant-type = [ ":" whsp1 expression ] [ whsp "|" whsp non-empty-union-type-or-literal ]

 

-; "( e )"

-parenthesized-expression = "(" whitespace expression ")"

 

+non-empty-list-literal = "[" whsp expression whsp *("," whsp expression whsp) "]"

 

-; All expressions end with trailing whitespace.  This just adds a final

-; whitespace prefix for the top-level of the program

-complete-expression = whitespace expression

+; This just adds surrounding whitespace for the top-level of the program

+complete-expression = whsp expression whsp

diff --git a/dhall_parser/src/dhall.pest.visibility b/dhall_parser/src/dhall.pest.visibility
index ee5ea2b..f881a50 100644
--- a/dhall_parser/src/dhall.pest.visibility
+++ b/dhall_parser/src/dhall.pest.visibility
@@ -1,5 +1,4 @@
-end_of_line
-# end_of_line_silent
+# end_of_line
 # tab
 # block_comment
 # block_comment_chunk
@@ -7,91 +6,71 @@ end_of_line
 # not_end_of_line
 # line_comment
 # whitespace_chunk
-# whitespace
-# whitespace_
-# nonempty_whitespace
+# whsp
+# whsp1
 # ALPHA
 # DIGIT
 # HEXDIG
 # simple_label_first_char
-# simple_label_next_other_char
 # simple_label_next_char
-# simple_label_start
 simple_label
 # quoted_label_char
 quoted_label
 label
+nonreserved_label
 # any_label
 double_quote_chunk
 double_quote_escaped
+double_quote_char
 double_quote_literal
 single_quote_continue
+escaped_quote_pair
+escaped_interpolation
+single_quote_char
 single_quote_literal
+interpolation
 # text_literal
-# if
-# then
-# else
-# let
-# in
-# as
-# using
-# merge
-missing
-# if_
+if_
 # then
 # else_
 # let_
-# in_
+in_
 # as_
 # using
-# merge
+merge
+missing
 # Infinity
+NaN
+Some
+# keyword
 Optional
 Text
 List
-# equal
-# or
-# plus
-# text_append
-# list_append
-# and
-# times
-# double_equal
-# not_equal
-# dot
-# bar
-# comma
-# at
-# colon
-# import_alt
-# open_parens
-# close_parens
-# close_parens
-# open_brace
-# close_brace
-# close_brace
-# open_bracket
-# close_bracket
-# close_bracket
-# open_angle
-# close_angle
-# close_angle
 # combine
 # combine_types
 # prefer
-# lambda
-# forall
-# arrow
+lambda
+forall
+arrow
 # exponent
+numeric_double_literal
+minus_infinity_literal
+plus_infinity_literal
 double_literal
 natural_literal
 integer_literal
 identifier
 # path_character
 # quoted_path_character
+unquoted_path_component
+quoted_path_component
 path_component
 path
 # local
+parent_path
+here_path
+home_path
+absolute_path
 scheme
 http_raw
 authority
@@ -108,7 +87,6 @@ authority
 # reg_name
 # pchar
 query
-fragment
 # pct_encoded
 # unreserved
 # sub_delims
@@ -121,17 +99,11 @@ import_type
 hash
 import_hashed
 import
-# expression
-lambda_expression
-ifthenelse_expression
-let_expression
-forall_expression
-arrow_expression
-merge_expression
-# empty_list_or_optional
+expression
+annotated_expression
+let_binding
 empty_collection
 non_empty_optional
-annotated_expression
 # operator_expression
 import_alt_expression
 or_expression
@@ -146,22 +118,24 @@ times_expression
 equal_expression
 not_equal_expression
 application_expression
-# atomic_expression
 # import_expression
 selector_expression
 selector
 labels
-# primitive_expression
-literal_expression
+primitive_expression
 # record_type_or_literal
 empty_record_literal
 empty_record_type
 non_empty_record_type_or_literal
 non_empty_record_type
+record_type_entry
 non_empty_record_literal
+record_literal_entry
 union_type_or_literal
 empty_union_type
 non_empty_union_type_or_literal
+union_literal_variant_value
+union_type_entry
+union_type_or_literal_variant_type
 non_empty_list_literal
-# parenthesized_expression
 # complete_expression