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Re: Programming language and IDE design

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On Sat, 16 Nov 2013 15:55:10 +0000, Martin Ward <martin@gkc.org.uk>
wrote:

>On Friday 08 Nov 2013 at 21:04, George Neuner <gneuner2@comcast.net> wrote:
>
>> The majority of successful languages are LL(k) for small k.  It's hard
>> to get much simpler than that for parsing.
>
>C is not LL(K), neither is COBOL, nor C++, nor I think is Java.
>That probably covers the majority of successful languages:
>if "success" is defined as "total lines of code in production".

They _all_ are LL(k).  More specifically, I believe all of your
examples are, at most, LL(2).

AFAIK, Fortran's DO loop requires the most lookahead of any of the
classic language features: LL(4) [if I'm counting correctly].

   10DOI=42
   10DOI=42,45

Card Fortran didn't require whitespace separation. You had to look
ahead to find [or not] the comma to distinguish DO "I = m,n" from the
assignment "DOI = n".


>> It's impossible not to have implementation dependent behavior: e.g.,
>> program execution time is a behavior that can't be specified.
>
>In my opinion, execution time is not part of the semantics or meaning
>of a program.

Then I hope never to encounter any devices you have programmed.


>Early CPUs did not have a hardware stack:  your attitude would suggest
>that *therefore* languages should define the behaviour of a recursive
>subroutine to be "implementation dependent".  Fortunately, there were
>language designers, such as the designers of Lisp and Algol,
>who recognised the value of recursion and included it in their language.
>As a result, hardware designers added stack operations to their CPUs.

I simply said that your assertion:

  (2) Absolutely no behaviour should be "implementation dependent"
      or "undefined". Every syntactically valid program should have
      a single semantically valid meaning (even if that meaning
      is "halt with an error message").

is not plausible.  I did not offer an alternative.


Since you brought up this ludicrous example, you ought to know that
the people who programmed those early CPUs - stack or no - were far
more aware of the program's runtime environment and of the tradeoffs
of using "equivalent" codings than you seem to want to be.

George
[Fortran through F77 potentially had to look arbitrarily far ahead to
tell FORMAT statements from an assignment to an array called FORMAT.
BTDT. But I would be surprised if any modern languages were that hard
to lex. -John]

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Re: Programming language and IDE design Martin Ward <martin@gkc.org.uk> - 2013-11-16 15:55 +0000
  Re: Programming language and IDE design Hans-Peter Diettrich <DrDiettrich1@aol.com> - 2013-11-16 19:48 +0100
  Re: Programming language and IDE design George Neuner <gneuner2@comcast.net> - 2013-11-18 19:02 -0500
    Re: Programming language and IDE design "Steven G. Kargl" <sgk@REMOVEtroutmask.apl.washington.edu> - 2013-11-19 15:36 +0000
    Re: Programming language and IDE design George Neuner <gneuner2@comcast.net> - 2013-11-19 12:41 -0500
      Re: Parsing Fortran, was Programming language and IDE design glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2013-11-19 20:18 +0000
        Re: Parsing Fortran, was Programming language and IDE design glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2013-11-21 21:22 +0000
    Re: Programming language and IDE design wclodius@earthlink.net (William Clodius) - 2013-11-22 18:27 -0700
    Re: Programming language and IDE design "robin" <robin51@dodo.com.au> - 2013-11-25 10:33 +1100
      Re: Programming language and IDE design Martin Ward <martin@gkc.org.uk> - 2013-12-03 15:15 +0000
        Re: Programming language and IDE design Hans-Peter Diettrich <DrDiettrich1@aol.com> - 2013-12-05 03:35 +0100
    Re: Programming language and IDE design hu47121@usenet.kitty.sub.org (Hannah) - 2014-03-02 00:03 +0000
      Re: LL vs LR, was Programming language and IDE design Ivan Godard <ivan@ootbcomp.com> - 2014-03-01 20:31 -0800
        Re: LL vs LR, was Programming language and IDE design Kaz Kylheku <kaz@kylheku.com> - 2014-03-02 18:41 +0000
      Re: Programming language and IDE design George Neuner <gneuner2@comcast.net> - 2014-03-02 12:21 -0500
  Re: Programming language and IDE design Jonathan Thornburg <jonathan@cobalt.astro.indiana.edu> - 2013-11-19 19:39 +0000

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