SuccessorML optional bar syntax

README.md

@@ -106,3 +106,9 @@ engine is the old version.
 
 `--debug-engine` enables debugging output, for developers. This flag requires
 that the `--preview-only` flag is also enabled.
+
+`-allow-top-level-exps [true|false]` (default `true`) controls whether or
+not top-level expressions (terminated by a semicolon) are allowed.
+
+`-allow-opt-bar [true|false]` (default `false`) controls whether or not
+SuccessorML optional bar syntax is allowed.

src/ast/AstType.sml

@@ -1,4 +1,4 @@
-(** Copyright (c) 2020-2021 Sam Westrick
+(** Copyright (c) 2020-2023 Sam Westrick
   *
   * See the file LICENSE for details.
   *)
@@ -171,6 +171,9 @@ struct
               } Seq.t
           (** the `|` delimiters between bindings *)
           , delims: Token.t Seq.t
+
+          (** SuccessorML: optional leading bar (not permitted in Standard ML). *)
+          , optbar: Token.t option
           } Seq.t
 
       (** the `and` delimiters between bindings *)
@@ -219,6 +222,9 @@ struct
 
           (** the `|` delimiters *)
           , delims: Token.t Seq.t
+
+          (** SuccessorML: optional leading bar (not permitted in Standard ML). *)
+          , optbar: Token.t option
           } Seq.t
 
       (** the `and` delimiters *)
@@ -303,6 +309,9 @@ struct
         , handlee: Token.t
         , elems: {pat: Pat.t, arrow: Token.t, exp: exp} Seq.t
         , delims: Token.t Seq.t (** the bars between match rules *)
+
+        (** SuccessorML: optional leading bar (not permitted in Standard ML). *)
+        , optbar: Token.t option
         }
 
     (** raise exp *)
@@ -328,13 +337,19 @@ struct
         , off: Token.t
         , elems: {pat: Pat.t, arrow: Token.t, exp: exp} Seq.t
         , delims: Token.t Seq.t (** the bars between match rules *)
+
+        (** SuccessorML: optional leading bar (not permitted in Standard ML). *)
+        , optbar: Token.t option
         }
 
     (** fn pat => exp [| pat => exp ...] *)
     | Fn of
         { fnn: Token.t
         , elems: {pat: Pat.t, arrow: Token.t, exp: exp} Seq.t
         , delims: Token.t Seq.t (** the bars between match rules *)
+
+        (** SuccessorML: optional leading bar (not permitted in Standard ML). *)
+        , optbar: Token.t option
         }
 
     (** things like _prim, _import, etc.
@@ -496,6 +511,8 @@ struct
             , elems: {vid: Token.t, arg: {off: Token.t, ty: Ty.t} option} Seq.t
             (** '|' delimiters between clauses *)
             , delims: Token.t Seq.t
+            (** SuccessorML: optional leading bar (not permitted in Standard ML). *)
+            , optbar: Token.t option
             } Seq.t
         (** 'and' delimiters between mutually recursive datatypes *)
         , delims: Token.t Seq.t

src/parse-mlb/ParseAllSMLFromMLB.sml

@@ -1,4 +1,4 @@
-(** Copyright (c) 2021 Sam Westrick
+(** Copyright (c) 2021-2023 Sam Westrick
   *
   * See the file LICENSE for details.
   *)
@@ -8,9 +8,14 @@ sig
   (** Take an .mlb source and fully parse all SML by loading all filepaths
     * recursively specified by the .mlb and parsing them, etc.
     *)
-  val parse: {pathmap: MLtonPathMap.t, skipBasis: bool, allowTopExp: bool}
-             -> FilePath.t
-             -> (FilePath.t * Parser.parser_output) Seq.t
+  val parse:
+    { pathmap: MLtonPathMap.t
+    , skipBasis: bool
+    , allowTopExp: bool
+    , allowOptBar: bool
+    }
+    -> FilePath.t
+    -> (FilePath.t * Parser.parser_output) Seq.t
 end =
 struct
 
@@ -65,7 +70,7 @@ struct
     TextIO.output (TextIO.stdErr, m)
 
   (** when skipBasis = true, we ignore paths containing $(SML_LIB) *)
-  fun parse {skipBasis, pathmap, allowTopExp} mlbPath :
+  fun parse {skipBasis, pathmap, allowTopExp, allowOptBar} mlbPath :
     (FilePath.t * Parser.parser_output) Seq.t =
     let
       open MLBAst
@@ -117,7 +122,8 @@ struct
                         handle OS.SysErr (msg, _) => errFun msg
 
               val (infdict, ast) =
-                Parser.parseWithInfdict {allowTopExp = allowTopExp}
+                Parser.parseWithInfdict
+                  {allowTopExp = allowTopExp, allowOptBar = allowOptBar}
                   (#fixities basis) src
             in
               ({fixities = infdict}, [(path, ast)])

src/parse/FixExpPrecedence.sml

@@ -1,4 +1,4 @@
-(** Copyright (c) 2020 Sam Westrick
+(** Copyright (c) 2020-2023 Sam Westrick
   *
   * See the file LICENSE for details.
   *)
@@ -103,11 +103,16 @@ struct
               }
           end
 
-      | Handle {exp, handlee, elems, delims} =>
+      | Handle {exp, handlee, elems, delims, optbar} =>
           let
             fun leftReplaceWith e =
               Handle
-                {exp = e, handlee = handlee, elems = elems, delims = delims}
+                { exp = e
+                , handlee = handlee
+                , elems = elems
+                , delims = delims
+                , optbar = optbar
+                }
           in
             F { prec = 7
               , left = SOME {exp = exp, replaceWith = leftReplaceWith}

src/parse/ParseExpAndDec.sml

@@ -1,4 +1,4 @@
-(** Copyright (c) 2020-2021 Sam Westrick
+(** Copyright (c) 2020-2023 Sam Westrick
   *
   * See the file LICENSE for details.
   *)
@@ -8,11 +8,12 @@ sig
   type ('a, 'b) parser = ('a, 'b) ParserCombinators.parser
   type tokens = Token.t Seq.t
 
-  val dec: {forceExactlyOne: bool}
+  val dec: {forceExactlyOne: bool, allowOptBar: bool}
            -> tokens
            -> (int * InfixDict.t, Ast.Exp.dec) parser
 
-  val exp: tokens
+  val exp: {allowOptBar: bool}
+           -> tokens
            -> InfixDict.t
            -> ExpPatRestriction.t
            -> (int, Ast.Exp.exp) parser
@@ -134,7 +135,7 @@ struct
     *)
 
 
-  fun dec {forceExactlyOne} toks (start, infdict) =
+  fun dec {forceExactlyOne, allowOptBar} toks (start, infdict) =
     let
       val numToks = Seq.length toks
       fun tok i = Seq.nth toks i
@@ -182,7 +183,7 @@ struct
         PC.zeroOrMoreWhile c p s
 
       fun consume_exp infdict restriction i =
-        exp toks infdict restriction i
+        exp {allowOptBar = allowOptBar} toks infdict restriction i
 
       fun consume_opvid infdict i =
         let
@@ -239,6 +240,10 @@ struct
               val (i, tyvars) = parse_tyvars i
               val (i, tycon) = parse_vid i
               val (i, eq) = parse_reserved Token.Equal i
+              val (i, optbar) = parse_maybeReserved Token.Bar i
+              val _ =
+                ParserUtils.checkOptBar allowOptBar optbar
+                  "Unexpected bar on first branch of datatype declaration."
 
               val (i, {elems, delims}) =
                 parse_oneOrMoreDelimitedByReserved
@@ -250,6 +255,7 @@ struct
                 , eq = eq
                 , elems = elems
                 , delims = delims
+                , optbar = optbar
                 }
               )
             end
@@ -461,11 +467,16 @@ struct
                 in
                   (i, {fname_args = fname_args, ty = ty, eq = eq, exp = exp})
                 end
-              val (i, func_def) =
+
+              val (i, optbar) = parse_maybeReserved Token.Bar i
+              val _ =
+                ParserUtils.checkOptBar allowOptBar optbar
+                  "Unexpected bar on first branch of 'fun'."
+              val (i, {elems, delims}) =
                 parse_oneOrMoreDelimitedByReserved
                   {parseElem = parseBranch, delim = Token.Bar} i
             in
-              (i, func_def)
+              (i, {elems = elems, delims = delims, optbar = optbar})
             end
 
           val funn = tok (i - 1)
@@ -686,7 +697,7 @@ struct
   (* ======================================================================= *)
 
 
-  and exp toks infdict restriction start =
+  and exp {allowOptBar} toks infdict restriction start =
     let
       val numToks = Seq.length toks
       fun tok i = Seq.nth toks i
@@ -708,6 +719,8 @@ struct
 
       fun parse_reserved rc i =
         PS.reserved toks rc i
+      fun parse_maybeReserved rc i =
+        PS.maybeReserved toks rc i
       fun parse_vid i = PS.vid toks i
       fun parse_longvid i = PS.longvid toks i
       fun parse_recordLabel i = PS.recordLabel toks i
@@ -727,7 +740,7 @@ struct
 
 
       fun consume_dec xx =
-        dec {forceExactlyOne = false} toks xx
+        dec {forceExactlyOne = false, allowOptBar = allowOptBar} toks xx
 
 
       fun consume_exp infdict restriction i =
@@ -1022,6 +1035,11 @@ struct
           val casee = tok (i - 1)
           val (i, exp) = consume_exp infdict Restriction.None i
           val (i, off) = parse_reserved Token.Of i
+          val (i, optbar) = parse_maybeReserved Token.Bar i
+          val _ =
+            ParserUtils.checkOptBar allowOptBar optbar
+              "Unexpected bar on first branch of 'case'."
+
           val (i, {elems, delims}) =
             parse_oneOrMoreDelimitedByReserved
               {parseElem = consume_matchElem infdict, delim = Token.Bar} i
@@ -1033,6 +1051,7 @@ struct
               , off = off
               , elems = elems
               , delims = delims
+              , optbar = optbar
               }
           )
         end
@@ -1057,11 +1076,19 @@ struct
       and consume_expFn infdict i =
         let
           val fnn = tok (i - 1)
+          val (i, optbar) = parse_maybeReserved Token.Bar i
+          val _ =
+            ParserUtils.checkOptBar allowOptBar optbar
+              "Unexpected bar on first branch of anonymous function."
+
           val (i, {elems, delims}) =
             parse_oneOrMoreDelimitedByReserved
               {parseElem = consume_matchElem infdict, delim = Token.Bar} i
         in
-          (i, Ast.Exp.Fn {fnn = fnn, elems = elems, delims = delims})
+          ( i
+          , Ast.Exp.Fn
+              {fnn = fnn, elems = elems, delims = delims, optbar = optbar}
+          )
         end
 
 
@@ -1132,12 +1159,21 @@ struct
       and consume_expHandle infdict exp i =
         let
           val handlee = tok (i - 1)
+          val (i, optbar) = parse_maybeReserved Token.Bar i
+          val _ =
+            ParserUtils.checkOptBar allowOptBar optbar
+              "Unexpected bar on first branch of 'handle'."
           val (i, {elems, delims}) =
             parse_oneOrMoreDelimitedByReserved
               {parseElem = consume_matchElem infdict, delim = Token.Bar} i
 
           val result = Ast.Exp.Handle
-            {exp = exp, handlee = handlee, elems = elems, delims = delims}
+            { exp = exp
+            , handlee = handlee
+            , elems = elems
+            , delims = delims
+            , optbar = optbar
+            }
 
           val result = FixExpPrecedence.maybeRotateLeft result
         in