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Re: specifying semantics, was Formatting of Language LRMs

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Ivan Godard <ivan@ootbcomp.com> writes:
>Well, conventionally the type system of a language is considered
>semantics, yet the whole Algol68 type system, including checking all
>expressions for type validity, is present in the VWG.

What is conventionally called "syntax" is an artifact of the compiler
technology (or maybe of specification technology, see below): Parsers
are based on context-free grammars, and anything that is not groked by
the parser is a syntax error, and what the parser accepts is
considered the syntax; and everything else is called the semantics.

And programming language specifications also follow that division:
most of them provide a context-free grammar, and provide everything
else in natural language.

However, "everything else" is a very wide category, and if you look
closer, you make further distinctions: There is static stuff and
run-time stuff; typically name lookups are done statically (you get an
error even if the code is not executed).  One may consider the static
stuff "syntax", but I think a more usual term is "static semantics".
I think the vW stuff in Algol 68 is also static stuff.

There is also the run-time semantics.

There have been some ways to specify static stuff.  vW grammars have
not caught on; attribute grammars are more successful, but for
compiler writers, not for language specifications; and even in
compilers attribute grammars are not very widely used.  It's mostly
just code in the compiler implementation language.

For the dynamic stuff, there has been quite a bit of academic work
(operational semantics, denotational semantics (although I think they
make little difference between static and dynamic stuff), but few uses
in language specifications or compilers.  I think Modula-3 used a
formal specification, but don't know about the type.

Generally, the problem of formal specifications is that, while they
may be precise, doing a complete formal specification is hard and they
are hard to understand (so it's easy to miss specification bugs).
Doing partial formal specifications for areas that are easier to
formally specify, and where the specifications are relatively easy to
understand has been much more successful (context-free grammars are to
most obvious example).  And the rest is filled in with natural
language.

- anton
--
M. Anton Ertl
anton@mips.complang.tuwien.ac.at
http://www.complang.tuwien.ac.at/anton/

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Thread

Formatting of Language LRMs Seima Rao <seimarao@gmail.com> - 2014-06-17 16:54 +0530
  Re: Formatting of Language LRMs "lpsantil@gmail.com" <lpsantil@gmail.com> - 2014-06-20 10:10 -0700
    Re: Formatting of Language LRMs glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2014-08-03 04:37 +0000
  Re: Formatting of Language LRMs Ivan Godard <ivan@ootbcomp.com> - 2014-06-20 12:09 -0700
    Re: Formatting of Language LRMs glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2014-06-21 02:27 +0000
    Re: Formatting of Language LRMs Kaz Kylheku <kaz@kylheku.com> - 2014-06-21 03:09 +0000
    Re: Formatting of Language LRMs Joshua Cranmer 🐧 <Pidgeot18@verizon.net.invalid> - 2014-06-22 21:12 -0500
      Re: VWG and K, was Formatting of Language LRMs Ivan Godard <ivan@ootbcomp.com> - 2014-06-22 21:47 -0700
      RE: Formatting of Language LRMs "Costello, Roger L." <costello@mitre.org> - 2014-07-03 09:06 +0000
        Re: Formatting of Language LRMs Ivan Godard <ivan@ootbcomp.com> - 2014-07-03 22:30 -0700
          Re: syntax checkers, was Formatting of Language LRMs glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2014-07-04 17:35 +0000
          Re: executable semantics, was Formatting of Language LRMs wclodius@earthlink.net (William Clodius) - 2014-07-04 15:53 -0600
  Re: specifying semantics, was Formatting of Language LRMs seimarao@gmail.com - 2014-06-24 02:19 -0700
    Re: specifying semantics, was Formatting of Language LRMs "lpsantil@gmail.com" <lpsantil@gmail.com> - 2014-06-24 13:12 -0700
    Re: specifying semantics, was Formatting of Language LRMs George Neuner <gneuner2@comcast.net> - 2014-06-26 00:54 -0400
      Re: specifying semantics, was Formatting of Language LRMs Andy Walker <news@cuboid.co.uk> - 2014-06-28 20:10 +0100
        Re: specifying semantics, was Formatting of Language LRMs George Neuner <gneuner2@comcast.net> - 2014-06-28 22:43 -0400
          Re: BNF, was specifying semantics wclodius@earthlink.net (William Clodius) - 2014-06-30 22:00 -0600
      Re: specifying semantics, was Formatting of Language LRMs Ivan Godard <ivan@ootbcomp.com> - 2014-06-28 12:25 -0700
        Re: specifying semantics, was Formatting of Language LRMs Andy Walker <news@cuboid.co.uk> - 2014-06-29 11:19 +0100
        Re: specifying semantics, was Formatting of Language LRMs George Neuner <gneuner2@comcast.net> - 2014-06-29 07:56 -0400
          Re: specifying semantics, was Formatting of Language LRMs Ivan Godard <ivan@ootbcomp.com> - 2014-06-29 11:49 -0700
            Re: specifying semantics, was Formatting of Language LRMs Gene Wirchenko <genew@telus.net> - 2014-06-30 18:09 -0700
              Re: specifying semantics, was Formatting of Language LRMs Ivan Godard <ivan@ootbcomp.com> - 2014-06-30 20:53 -0700
                Re: Algol history, was specifying semantics anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2014-07-03 11:51 +0000
                Re: Algol history, was specifying semantics Ivan Godard <ivan@ootbcomp.com> - 2014-07-03 22:20 -0700
                Re: Algol history, was specifying semantics wclodius@earthlink.net (William Clodius) - 2014-07-04 15:52 -0600
                Re: Algol history, was specifying semantics glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2014-07-07 05:49 +0000
                Re: Algol history, was specifying semantics Ivan Godard <ivan@ootbcomp.com> - 2014-07-07 10:48 -0700
                Re: Algol history, was specifying semantics glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2014-07-07 19:49 +0000
                Re: Algol history, was specifying semantics glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2014-07-07 19:43 +0000
                Re: specifying semantics, was Formatting of Language LRMs Gene Wirchenko <genew@telus.net> - 2014-07-03 21:44 -0700
            Re: specifying semantics, was Formatting of Language LRMs anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2014-07-02 09:51 +0000
              Re: specifying semantics, was Formatting of Language LRMs Stefan Monnier <monnier@iro.umontreal.ca> - 2014-07-03 10:15 -0400
                Re: specifying semantics, was Formatting of Language LRMs glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2014-07-04 06:08 +0000
                Re: specifying semantics, was Formatting of Language LRMs Hans-Peter Diettrich <DrDiettrich1@aol.com> - 2014-07-04 08:51 +0200
                Re: Parsing Fortran, was specifying semantics glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2014-07-04 17:53 +0000
                Re: Parsing Fortran, was specifying semantics wclodius@earthlink.net (William Clodius) - 2014-07-04 15:57 -0600
  Re: Formatting of Language LRMs mertesthomas@gmail.com - 2014-06-30 12:04 -0700
  Re: Formatting of Language LRMs federation2005@netzero.com - 2014-07-28 17:55 -0700
    Re: Formatting of Language LRMs federation2005@netzero.com - 2014-08-01 14:58 -0700

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