NAME

       smlyacc - the parser generator for SML#

SYNOPSIS

       smlyacc [-s] [-p output_prefix] filename

DESCRIPTION

       SMLYacc is a parser generator in the style of ML-Yacc.  It can accept grammer files of ML-
       Yacc, but generated programs and their usage are  not  compatible  to  those  of  ML-Yacc.
       Generated programs can be compiled by the SML# compiler.

       By default, for an input file X.grm, smlyacc generates X.grm.sml for the generated parser,
       X.grm.sig for the signature of tokens, and optionally X.grm.desc for  the  description  of
       LALR  parser  construction.  To compile the generated program with SML#, you need to write
       an inteface file X.grm.smi by yourself according to the generated signature X.grm.sig.

   OPTIONS
       -s     Insert the token signature at the beginning of the generated .sml file, instead  of
              a separate .sig file.

       -p output_prefix
              Set  the  prefix of the output file names.  When output_prefix is set to X, smlyacc
              generates X.sml, X.sig, and X.desc.  The default is the  same  as  the  input  file
              name.

EXAMPLES

       The following is a minimal example of an input file ex.grm:

              %%
              %term LPAREN | RPAREN | EOF
              %nonterm start of word | exp of word
              %pos int
              %eop EOF
              %name Example
              %%
              start : exp (exp)
              exp : (0w0)
                  | LPAREN exp RPAREN exp (exp1 + exp2)

       By applying this file to smlyacc,

              smlyacc ex.grm

       you obtain two files ex.grm.sml and ex.grm.sig.  Only ex.grm.sml needs to be compiled.  To
       compile it, you need to create the following ex.grm.smi file by yourself:

              _require "basis.smi"
              _require local "ml-yacc-lib.smi"
              _require local "./ex.grm.sig"
              structure ExampleLrVals =
              struct
                structure Parser =
                struct
                  type token (= boxed)
                  type stream (= ref)
                  type result = word
                  type pos = int
                  type arg = unit
                  val makeStream : {lexer : unit -> token} -> stream
                  val consStream : token * stream -> stream
                  val getStream : stream -> token * stream
                  val sameToken : token * token -> bool
                  val parse : {lookahead : int,
                               stream : stream,
                               error : string * pos * pos -> unit,
                               arg : arg}
                              -> result * stream
                end
                structure Tokens =
                struct
                  type pos = Parser.pos
                  type token = Parser.token
                  val EOF: pos * pos -> token
                  val RPAREN: pos * pos -> token
                  val LPAREN: pos * pos -> token
                end
              end

       The types of token constructors (EOF, RPAREN, and LPAREN) are copied  from  the  generated
       signature ex.grm.sig file by hand.

       The  parse  function  in the generated program is the parser.  To invoke it, an imperative
       lexer function of type unit -> token is needed.  In the case of combining with SMLLex, the
       lexer  is  generated  by  SMLLex.   Suppose that SMLLex generates a lexer of the following
       interface:

              structure ExampleLex =
              struct
                exception LexError
                val makeLexer : (int -> string)
                                -> unit -> ExampleLrVals.Parser.token
              end

       A typical code joining SMLLex and SMLYacc looks like the following:

              fun inputN n = TextIO.inputN (instream, n)
              val lexer = ExampleLex.makeLexer inputN
              val stream = ExampleLrVals.Parser.makeStream {lexer = lexer}
              val (result, stream) =
                  ExampleLrVals.parse
                    {lookahead = 0, stream = stream,
                     error = errorFn, arg = parserArg}

HISTORY

       SMLYacc is a derivative of ML-Yacc, which is originally developed by David R. Tarditi  and
       Andrew  W.  Appel.   When  ML-Yacc was ported to SML#, the source code was restructured to
       replace functor applications with SML#'s separate compilation and linking.  See  the  SML#
       document for major changes from the original ML-Yacc.

SEE ALSO

       smllex(1)
       ML-Yacc User's Manual, available at https://www.smlnj.org/doc/ML-Yacc/
       SML# Document, available at https://www.pllab.riec.tohoku.ac.jp/smlsharp/docs/

                                                                                       SMLYACC(1)