src/Pure/Syntax/syntax.ML

   val string_of_term_global: theory -> term -> string
   val string_of_typ_global: theory -> typ -> string
   val string_of_sort_global: theory -> sort -> string
   type syntax
   val eq_syntax: syntax * syntax -> bool
+  val join_syntax: syntax -> unit
   val lookup_const: syntax -> string -> string option
   val is_keyword: syntax -> string -> bool
   val tokenize: syntax -> bool -> Symbol_Pos.T list -> Lexicon.token list
   val parse: Proof.context -> syntax -> string -> Lexicon.token list -> Parser.parsetree list
   val parse_ast_translation: syntax -> string -> (Proof.context -> Ast.ast list -> Ast.ast) option

     print_ast_trtab: ((Proof.context -> Ast.ast list -> Ast.ast) * stamp) list Symtab.table,
     prtabs: Printer.prtabs} * stamp;
 
 fun eq_syntax (Syntax (_, s1), Syntax (_, s2)) = s1 = s2;
 
+fun join_syntax (Syntax ({gram, ...}, _)) = ignore (Future.join gram);
+
 fun lookup_const (Syntax ({consts, ...}, _)) = Symtab.lookup consts;
 fun is_keyword (Syntax ({lexicon, ...}, _)) = Scan.is_literal lexicon o Symbol.explode;
 fun tokenize (Syntax ({lexicon, ...}, _)) = Lexicon.tokenize lexicon;
 fun parse ctxt (Syntax ({gram, ...}, _)) = Parser.parse ctxt (Future.join gram);