Re: Double and FP syntax (was: Decimal Point vs. Decimal Comma)

From	anton@mips.complang.tuwien.ac.at (Anton Ertl)
Newsgroups	comp.lang.forth
Subject	Re: Double and FP syntax (was: Decimal Point vs. Decimal Comma)
Date	2016-04-24 16:03 +0000
Organization	Institut fuer Computersprachen, Technische Universitaet Wien
Message-ID	<2016Apr24.180330@mips.complang.tuwien.ac.at> (permalink)
References	(7 earlier) <dt6dnUt7ENie6JrKnZ2dnUU7-bmdnZ2d@supernews.com> <2016Apr8.122641@mips.complang.tuwien.ac.at> <ne9ao1$2gt$1@dont-email.me> <2016Apr9.111900@mips.complang.tuwien.ac.at> <5710b523.80478700@news.eternal-september.org>

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stephen@mpeforth.com (Stephen Pelc) writes:
>On Sat, 09 Apr 2016 09:19:00 GMT, anton@mips.complang.tuwien.ac.at
>(Anton Ertl) wrote:
>>The general idea to go away from "." for doubles and use something
>>else is in the right direction, yes.  The general idea of DP-CHAR is
>>bad, as demonstrated above.
>
>This debate has been going on for over 25 years. It's about being able
>to use our tools in applications, e.g. number conversion data during
>data entry, and when the need occurs, e.g. compile-time and run-time.
>A secondary need is to make numbers easy to read.
>
>In ANS and Forth-2012, allowing for common practice, we need to be
>able to set
>  double number indicator, usually ',' or '.'

In Forth-94 and -2012, just a trailing ".".

However, getting back to the original question of an alternative way
to indicate doubles, a leading ",", i.e.,

,1234

might be another way.  It is already supported by several systems,
does not have the conflict with "2," or any other conflict I know of.
A disadvantige is the small visual distance from ".", but if used only
as a prefix, the difference is hopefully big enough.

>  floating point indicator, usually '.' for English speakers

And for programmers in general; but not in standard Forth.  The
conflict of that with the standard double indicator is the reason for
this thread.

>  ignored characters, typically '_' and/or ':'

I don't see any conflicts involving '_', but ':' is often used in time
specifications.

>The ignored characters are usually used for hex numbers in bit masks
>and addresses in embedded systems code, e.g.
>  $2000:0000 equ RAM-BASE
>Ignorable characters are even more useful for 64 bit systems.
>
>VFX has 4-byte arrays
>  DP-CHAR
>  FP-CHAR
>  IGN-CHAR
>They are just the mechanism. They are there because of customer 
>request.

The customers requested exactly this mechanism?  If so, it shows that
customers are not always so great at devising solutions for their
problems.

>Being able to change these is no worse than being able to change
>BASE.

Right, making these variables part of the interface is just as bad as
making BASE part of the interface.  Unfortunately, BASE is standard,
so we cannot easily avoid this particular mistake, we can offer ways
to avoid it by providing number prefixes (in Forth-2012) and words
like BASE-EXECUTE (not standardized).  Anyway, the experience with
BASE is a good reason to avoid DP-CHAR etc.

>If we go back to Elizabeth's telephone number example to treat
>punctuation as double number indicators, then we need to be able
>to set a suitable list of indicators/separators.

Her telephone number example does not work for countries that can have
significant leading zeroes in telephone numbers (all countries known
to me).  We have a better way to deal with that: recognizers (in the
RfD stage).

>>The syntax is something we have to decide as a community.  Chickening
>>out by providing configuration options (and worse, as global state) to
>>individual programmers only leads to problems.  System implementors
>>may decide to inflict such problems on their users by providing such
>>options in order to support legacy code (but a conversion tool would
>>be better), but such kludges have no place in the standard.
>
>We are not supporting legacy code. We are supporting application
>need.

There is non-legacy application need to switch around between
different interpretations of "1234." in the text interpreter?  What
application need is that?

In particular, and related to the topic, is there a non-legacy
application need to text-interpret "1234." as a double number once we
provide a standard alternative syntax?

>We are exposing rather than burying our tools.

Rule #14 in Forth discussions: If you provide a bad interface rather
than working on a good interface, justify it with "not burying your
tools".

>And this where we disagree. Options can be set, and a word provided
>to restore standard behaviour. It's no worse than HEX ... DECIMAL.

Which are pretty bad.

>These options exist because there is a need for them.

For me, not any longer in program text.

>This discussion is in the same place as recognisers, which can
>unleash a whole new world of features and pain.

True, one can write a recognizer that uses DP-CHAR etc.  One can
certainly write completely non-sensical recognizers, just as one can
write non-sensical Forth programs.

But the point is not to prevent people from shooting themselves in the
foot if they want to, but to give them ways to avoid doing that
accidentially.  And I think that recognizers, even in their current
raw state, are much better at this than BASE and DP-CHAR.  I had
several occurences of accidentially shooting myself in the foot with
BASE (typically in some program written by someone else), and one
where a trailing "," as double indicator resulted in foot-shooting.

By contrast, I have not yet had one occurence where the new number
prefix recognizers resulted in foot-shooting.  Why not?  Because they
were chosen to avoid conflicts.

Now for the user-defined recognizers, I expect that responsible
programmers will define recognizers that are unlikely to lead to
conflicts.  If there are conflicts, there's a recognizer stack that
specifies how to resolve the conflict.

Of course, this being Forth, there will still be cowboy programmers
that define recognizers that match pretty much everything, or that use
configuration variables like DP-CHAR to configure what is matched, but
at least there is a way to do better for programmers who want to do
better.

>A word to restore
>standard behaviour is still needed, e.g.
>  STANDARD-NUMBERS ( -- )

In the context of recognizers, you just put the word, number, and FP
recognizers on the recognizer stack.  However, this kind of global
reset is not useful in the context of reusable code.

- anton
-- 
M. Anton Ertl  http://www.complang.tuwien.ac.at/anton/home.html
comp.lang.forth FAQs: http://www.complang.tuwien.ac.at/forth/faq/toc.html
     New standard: http://www.forth200x.org/forth200x.html
   EuroForth 2015: http://www.rigwit.co.uk/EuroForth2015/

Thread

Decimal Point vs. Decimal Comma rickman <gnuarm@gmail.com> - 2016-04-02 17:49 -0400
  Re: Decimal Point vs. Decimal Comma anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2016-04-03 06:23 +0000
    Re: Decimal Point vs. Decimal Comma rickman <gnuarm@gmail.com> - 2016-04-03 02:59 -0400
    Re: Decimal Point vs. Decimal Comma Coos Haak <chforth@hccnet.nl> - 2016-04-03 17:33 +0200
      Re: Decimal Point vs. Decimal Comma "Elizabeth D. Rather" <erather@forth.com> - 2016-04-03 21:21 -1000
        Re: Decimal Point vs. Decimal Comma Paul Rubin <no.email@nospam.invalid> - 2016-04-04 01:42 -0700
          Re: Decimal Point vs. Decimal Comma hughaguilar96@gmail.com - 2016-04-04 02:00 -0700
            Re: Decimal Point vs. Decimal Comma Albert van der Horst <albert@spenarnc.xs4all.nl> - 2016-04-04 10:00 +0000
              Re: Decimal Point vs. Decimal Comma hughaguilar96@gmail.com - 2016-04-04 03:04 -0700
              Re: Decimal Point vs. Decimal Comma "Elizabeth D. Rather" <erather@forth.com> - 2016-04-04 11:16 -1000
          Re: Decimal Point vs. Decimal Comma "Elizabeth D. Rather" <erather@forth.com> - 2016-04-03 23:28 -1000
            Re: Decimal Point vs. Decimal Comma Paul Rubin <no.email@nospam.invalid> - 2016-04-04 02:38 -0700
              Re: Decimal Point vs. Decimal Comma "Elizabeth D. Rather" <erather@forth.com> - 2016-04-04 11:09 -1000
            Re: Decimal Point vs. Decimal Comma "HAA" <someone@microsoft.com> - 2016-04-08 00:18 +1000
              Re: Decimal Point vs. Decimal Comma Andrew Haley <andrew29@littlepinkcloud.invalid> - 2016-04-08 03:27 -0500
                Re: Decimal Point vs. Decimal Comma anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2016-04-08 08:30 +0000
                Re: Decimal Point vs. Decimal Comma Ron Aaron <rambamist@gmail.com> - 2016-04-08 12:00 +0300
                Re: Decimal Point vs. Decimal Comma anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2016-04-08 10:25 +0000
                Re: Decimal Point vs. Decimal Comma Ron Aaron <rambamist@gmail.com> - 2016-04-08 13:34 +0300
                Re: Decimal Point vs. Decimal Comma anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2016-04-08 11:46 +0000
                Re: Decimal Point vs. Decimal Comma Ron Aaron <rambamist@gmail.com> - 2016-04-08 15:20 +0300
                Re: Decimal Point vs. Decimal Comma Andrew Haley <andrew29@littlepinkcloud.invalid> - 2016-04-08 04:08 -0500
                Re: Decimal Point vs. Decimal Comma anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2016-04-08 10:26 +0000
                Re: Decimal Point vs. Decimal Comma Andrew Haley <andrew29@littlepinkcloud.invalid> - 2016-04-08 10:37 -0500
                Re: Decimal Point vs. Decimal Comma anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2016-04-09 15:28 +0000
                Re: Decimal Point vs. Decimal Comma Paul Rubin <no.email@nospam.invalid> - 2016-04-09 10:17 -0700
                Re: Decimal Point vs. Decimal Comma anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2016-04-11 14:45 +0000
                Re: Decimal Point vs. Decimal Comma Ron Aaron <rambamist@gmail.com> - 2016-04-12 10:18 +0300
                Re: Decimal Point vs. Decimal Comma hughaguilar96@gmail.com - 2016-04-08 09:05 -0700
                Re: Decimal Point vs. Decimal Comma hughaguilar96@gmail.com - 2016-04-08 10:14 -0700
                Re: Decimal Point vs. Decimal Comma Julian Fondren <julian.fondren@gmail.com> - 2016-04-08 15:51 -0700
                Re: Decimal Point vs. Decimal Comma Julian Fondren <julian.fondren@gmail.com> - 2016-04-08 16:11 -0700
                Re: Decimal Point vs. Decimal Comma "WJ" <w_a_x_man@yahoo.com> - 2016-05-09 01:16 +0000
                Re: Decimal Point vs. Decimal Comma Bernd Paysan <bernd.paysan@gmx.de> - 2016-04-08 22:18 +0000
                Re: Decimal Point vs. Decimal Comma Paul Rubin <no.email@nospam.invalid> - 2016-04-08 20:33 -0700
                Re: Decimal Point vs. Decimal Comma mhx@iae.nl - 2016-04-09 01:20 -0700
                Re: Decimal Point vs. Decimal Comma anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2016-04-09 11:03 +0000
                Re: Decimal Point vs. Decimal Comma mhx@iae.nl - 2016-04-09 01:29 -0700
                Double and FP syntax (was: Decimal Point vs. Decimal Comma) anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2016-04-09 09:19 +0000
                Re: Double and FP syntax "Elizabeth D. Rather" <erather@forth.com> - 2016-04-09 14:25 -1000
                Re: Double and FP syntax hughaguilar96@gmail.com - 2016-04-10 21:48 -0700
                Re: Double and FP syntax (was: Decimal Point vs. Decimal Comma) stephen@mpeforth.com (Stephen Pelc) - 2016-04-15 10:17 +0000
                Re: Double and FP syntax (was: Decimal Point vs. Decimal Comma) hughaguilar96@gmail.com - 2016-04-17 16:48 -0700
                Re: Double and FP syntax (was: Decimal Point vs. Decimal Comma) anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2016-04-24 16:03 +0000
        Re: Decimal Point vs. Decimal Comma Albert van der Horst <albert@spenarnc.xs4all.nl> - 2016-04-04 09:27 +0000
      Re: Decimal Point vs. Decimal Comma Albert van der Horst <albert@spenarnc.xs4all.nl> - 2016-04-04 08:52 +0000
    Re: Decimal Point vs. Decimal Comma Bernd Paysan <bernd.paysan@gmx.de> - 2016-04-03 23:14 +0000
      Re: Decimal Point vs. Decimal Comma Ron Aaron <rambamist@gmail.com> - 2016-04-04 07:18 +0300
        Re: Decimal Point vs. Decimal Comma Ron Aaron <rambamist@gmail.com> - 2016-04-04 07:48 +0300
  Re: Decimal Point vs. Decimal Comma upsidedown@downunder.com - 2016-04-03 09:45 +0300
  Re: Decimal Point vs. Decimal Comma Nils M Holm <nmh@ananda.local> - 2016-04-03 07:32 +0000
  Re: Decimal Point vs. Decimal Comma George Neuner <gneuner2@comcast.net> - 2016-04-03 05:25 -0400
    Re: Decimal Point vs. Decimal Comma Robert Wessel <robertwessel2@yahoo.com> - 2016-04-03 17:22 -0500
  Re: Decimal Point vs. Decimal Comma Norbert_Paul <norbertpauls_spambin@yahoo.com> - 2016-04-03 14:05 +0200
  Re: Decimal Point vs. Decimal Comma Hans-Bernhard Bröker <HBBroeker@t-online.de> - 2016-04-03 14:18 +0200
    Re: Decimal Point vs. Decimal Comma upsidedown@downunder.com - 2016-04-03 20:24 +0300
      Re: Decimal Point vs. Decimal Comma Niklas Holsti <niklas.holsti@tidorum.invalid> - 2016-04-03 21:05 +0300
        Re: Decimal Point vs. Decimal Comma Albert van der Horst <albert@spenarnc.xs4all.nl> - 2016-04-04 09:00 +0000
      Re: Decimal Point vs. Decimal Comma Ron Aaron <rambamist@gmail.com> - 2016-04-03 21:16 +0300
        Re: Decimal Point vs. Decimal Comma Albert van der Horst <albert@spenarnc.xs4all.nl> - 2016-04-04 09:17 +0000
          Re: Decimal Point vs. Decimal Comma Ron Aaron <rambamist@gmail.com> - 2016-04-04 12:46 +0300
            Re: Decimal Point vs. Decimal Comma anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2016-04-05 06:02 +0000
      Re: Decimal Point vs. Decimal Comma Bernd Paysan <bernd.paysan@gmx.de> - 2016-04-03 23:21 +0000
        Re: Decimal Point vs. Decimal Comma anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2016-04-04 07:11 +0000
          Re: Decimal Point vs. Decimal Comma Bernd Paysan <bernd.paysan@gmx.de> - 2016-04-04 21:11 +0000
      Re: Decimal Point vs. Decimal Comma hughaguilar96@gmail.com - 2016-04-03 19:27 -0700
      Re: Decimal Point vs. Decimal Comma Robert Wessel <robertwessel2@yahoo.com> - 2016-04-04 00:13 -0500
        Re: Decimal Point vs. Decimal Comma "Boudewijn Dijkstra" <sp4mtr4p.boudewijn@indes.com> - 2016-04-04 14:06 +0200
      Re: Decimal Point vs. Decimal Comma Nobody <nobody@nowhere.invalid> - 2016-04-05 03:32 +0100
        Re: Decimal Point vs. Decimal Comma hughaguilar96@gmail.com - 2016-04-04 19:52 -0700
        Re: Decimal Point vs. Decimal Comma upsidedown@downunder.com - 2016-04-05 09:56 +0300
          Re: Decimal Point vs. Decimal Comma hughaguilar96@gmail.com - 2016-04-05 00:13 -0700
            Re: Decimal Point vs. Decimal Comma anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2016-04-05 09:44 +0000
              Re: Decimal Point vs. Decimal Comma Albert van der Horst <albert@spenarnc.xs4all.nl> - 2016-04-05 12:38 +0000
          Re: Decimal Point vs. Decimal Comma Albert van der Horst <albert@spenarnc.xs4all.nl> - 2016-04-05 10:03 +0000
            Re: Decimal Point vs. Decimal Comma Bernd Paysan <bernd.paysan@gmx.de> - 2016-04-05 21:42 +0000
          Re: Decimal Point vs. Decimal Comma George Neuner <gneuner2@comcast.net> - 2016-04-05 11:11 -0400
            Re: Decimal Point vs. Decimal Comma Andrew Haley <andrew29@littlepinkcloud.invalid> - 2016-04-05 11:33 -0500
            Re: Decimal Point vs. Decimal Comma hughaguilar96@gmail.com - 2016-04-05 11:58 -0700
            Re: Decimal Point vs. Decimal Comma anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2016-04-06 12:50 +0000
        Re: Decimal Point vs. Decimal Comma anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2016-04-05 07:15 +0000
          Re: Decimal Point vs. Decimal Comma hughaguilar96@gmail.com - 2016-04-05 01:12 -0700
          Re: Decimal Point vs. Decimal Comma Bernd Paysan <bernd.paysan@gmx.de> - 2016-04-05 21:50 +0000
            Re: Decimal Point vs. Decimal Comma Dimiter_Popoff <dp@tgi-sci.com> - 2016-04-06 01:18 +0300
              Re: Decimal Point vs. Decimal Comma hughaguilar96@gmail.com - 2016-04-05 23:47 -0700
              Re: Decimal Point vs. Decimal Comma Bernd Paysan <bernd.paysan@gmx.de> - 2016-04-08 23:11 +0000
                Re: Decimal Point vs. Decimal Comma Dimiter_Popoff <dp@tgi-sci.com> - 2016-04-09 03:19 +0300
                Re: Decimal Point vs. Decimal Comma hughaguilar96@gmail.com - 2016-04-08 22:06 -0700
                Re: Decimal Point vs. Decimal Comma mac <acolvin@efunct.com> - 2016-04-11 18:52 +0000
                Re: Decimal Point vs. Decimal Comma Dimiter_Popoff <dp@tgi-sci.com> - 2016-04-11 23:39 +0300
  Re: Decimal Point vs. Decimal Comma endlessboomcapitalism@gmail.com - 2016-05-02 15:29 -0700
    Re: Decimal Point vs. Decimal Comma rickman <gnuarm@gmail.com> - 2016-05-02 22:27 -0400
      Re: Decimal Point vs. Decimal Comma Gerard Sontag <gerardsontag@gmail.com> - 2016-05-03 05:06 -0700
      Re: Decimal Point vs. Decimal Comma Bernd Paysan <bernd.paysan@gmx.de> - 2016-05-06 23:42 +0000
        Re: Decimal Point vs. Decimal Comma rickman <gnuarm@gmail.com> - 2016-05-06 20:37 -0400

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