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Re: [ddlm-group] Space as a list item separator

Dear Colleagues,

   Nothing is gained by dropping the commas, and at this point,
after having them in the spec since 2006, taking them out looks
like change for the sake of change, not for any useful purpose.

   There is the simple reality, that people are used to lists
presented two ways, in matrices and vectors of numbers with blanks,
and in lists of words and strings with commas, and then, from
habit of mainly working with one or the other, entirely with
blanks or entirely with commas.

   In addition, for the table parse, you have to allow for the colon.

   So, why not, in this one small way, in the otherwise rather 
user-unfriendly CIF 2 that is devoloping, to show just one small kindness
to users as the expense of adding one minor branch to the lexical scan
and allow both blanks and commas in handling lists?

   I vote for spaces and commas.

   I vote to treat the missing separator case as a minor warning case,
otherwise to be processed as what the user clearly intented, i.e.

  [[1 2 3][4 5 6]]

[[1 2 3] [4 5 6]]

[[1 2 3],[4 5 6]]

[[1,2,3] [4,5,6]]

[[1,2,3],[4,5,6]]

[[1 2 3]
  [4 5 6]]

[[1, 2, 3]
  [4, 5, 6]]

would all be equivalent, but a parse in fussy mode might
give a warning in the first case

I would greatly prefer that the empty list element case

{a,,b}

would be equivalent to

{a,.,b} and {a,?,b} and {a . b} and {"a",  ,"b"}


   Regards,
     Herbert

P.S.  The more I think about it, the more I believe that having a 
minimally disruptive CIF 1.5 (CIF 1.1 plus dREL using CIF 2 dictionaries) 
will be essential to community acceptance of a transition to CIF 2.

=====================================================
  Herbert J. Bernstein, Professor of Computer Science
    Dowling College, Kramer Science Center, KSC 121
         Idle Hour Blvd, Oakdale, NY, 11769

                  +1-631-244-3035
                  yaya@dowling.edu
=====================================================

On Sat, 28 Nov 2009, James Hester wrote:

> It seems that most of us are in favour of spaces as separators, with Herbert
> at least in favour of spaces and commas.  Some things to decide:
> 
> 1. Do we want spaces and commas, or only spaces?
> 2. Space syntax: while all primitive values should be separated from
> neighbouring primitive values by spaces, what about compound values (i.e.
> lists).  So for example, is
> 
> [[1 2 3][4 5 6]]
> 
> acceptable or should it be
> 
> [[1 2 3] [4 5 6]] ?
> 
> (I have added a space between the neighbouring lists in the second version).
> 
> 3.  If commas are acceptable, we need to decide on the two cases that I
> brought up recently: are multiple commas in a row acceptable (like
> [1,,2,3])?  Are trailing commas acceptable - [1,2,3,]?  Herbert appears to
> favour inferring a missing value in these cases, and Nick thinks they should
> both be syntax errors.  I favour Nick's interpretation, and Herbert's
> interpretations could then be coercion rules.  Of course, if we drop commas
> altogether, this is a moot point.
> 
> My votes would be:
> 
> For 1: prefer spaces only, but absolutely no problems with including commas
> if that is what is preferred by the rest of you.  My preference for spaces
> only is entirely for simplicity and consistency with the rest of the CIF
> syntax.
> For 2: allow non-primitive values to have no space between them
> For 3: as I said, these examples should be syntax errors.
> 
> Simon: I sincerely hope we have not dropped space as a separator in CIF2; we
> have reduced its role as a delimiter, which makes it possible to recover
> from certain syntax errors and ever so slightly simplifies the grammar.
> 
> On Sat, Nov 28, 2009 at 9:01 PM, SIMON WESTRIP <simonwestrip@btinternet.com>
> wrote:
>       I had been under the assumption that the separation of list
>       items by a comma was 'set in stone'
>       (and was one reason for dropping the CIF1 syntax of requiring
>       space after data values),
>       but if its up for negotiation I would opt for using the space as
>       a separator as elsewhere in the CIF,
>       partly because then a list can essentially be treated much like
>       a single-item loop - i.e. same basic parsing
>       of <value><space><value><space>...
>
>       Cheers
>
>       Simon
> 
> ____________________________________________________________________________
> From: Herbert J. Bernstein <yaya@bernstein-plus-sons.com>
> To: Group finalising DDLm and associated dictionaries
> <ddlm-group@iucr.org>
> Cc: Nick.Spadaccini@uwa.edu.au
> Sent: Friday, 27 November, 2009 11:43:10
> 
> Subject: Re: [ddlm-group] Space as a list item separator
> 
> Dear Colleagues,
> 
>   I have no objection to accepting either comma or whitespace
> as a valid separator in a list.  I can't object -- I have been
> coding to that standard since 1997, and now would only have to
> remove the message generated for the case of the space.  We already
> accept multiple glyphs as valid separators at all levels:
> 
>   whitespace itself it one of several character sequences in rather
> complex combinations:  any number of blanks, tabs, newlines and
> comments.
> The comma itself is handled in a complex way.  We accept (or should
> accept) any whitespace before and after a comma as valid, as in
> {a,b} versus {a , b }.  Adding the option of leaving out the comma
> itself and just having the whitespace as the separator make just
> as much sense.
> 
>   I see nothing to be gained by now forbidding the comma.  The meaning
> of {a,,b,} is the same as {a,.,b,.} or {a,?,b,?} or, under this new
> (and I think more sensibsle and realistic approach) {a . b .} or {a ?
> b ?}.
> 
>   The blank reads particularly well in dealing with vectors and
> matrices. The comma reads well when dealing with strings.
> 
>   I think we would do best with both as valid alternatives (no error,
> no warning for either one).
> 
>   Regards,
>     Herbert =====================================================
> Herbert J. Bernstein, Professor of Computer Science
>   Dowling College, Kramer Science Center, KSC 121
>         Idle Hour Blvd, Oakdale, NY, 11769
> 
>                 +1-631-244-3035
>                 yaya@dowling.edu
> =====================================================
> 
> On Fri, 27 Nov 2009, SIMON WESTRIP wrote:
> 
> > At first glance, you're considering using space instead of commas as
> list
> > separators?
> > which is not so far away from the CIF1 requirement of space
> following a
> > delimiter?
> >
> > But I'm only on my first cup of coffee this morning :-)
> >
> >___________________________________________________________________________
> _
> > From: Nick Spadaccini <nick@csse.uwa.edu.au>
> > To: Group finalising DDLm and associated dictionaries
> <ddlm-group@iucr.org>
> > Sent: Friday, 27 November, 2009 7:46:44
> > Subject: Re: [ddlm-group] Space as a list item separator
> >
> >
> >
> >
> > On 27/11/09 2:32 PM, "James Hester" <jamesrhester@gmail.com> wrote:
> >
> > > See comments below:
> > >
> > > On Fri, Nov 27, 2009 at 3:09 PM, Nick Spadaccini
> <nick@csse.uwa.edu.au>
> > wrote:
> > >> Timely email, come in just after the one I sent.
> > >>
> > >> My position is if we specify the syntax then we encourage its
> correct use
> > but
> > >> acknowledge that there may be cases where one might be able to
> recover
> > >> intent. But I wouldn?t encourage those cases.
> > >
> > > Absolutely, which is why I would like to elevate space-separated
> list
> > items to
> > > be correct syntax rather than 'wrong but intent is clear' syntax.
> > >>
> > >> You could say that token separator in lists are a or b or c, but
> that
> > just
> > >> adds a level of complexity for very little gain. The choice of
> comma
> > makes it
> > >> seamless to translate from the raw CIF data straight in to most
> language
> > >> specific data declaration. The only language I know that accepts
> one or
> > the
> > >> other or both is MatLab.
> > >
> > > Re ease of translation: you speak as if a viable approach to a CIF
> data
> > file
> > > is to take whole text chunks and throw them at some language
> interpreter,
> > > without doing your own parse.  Quite apart from being a rather
> unlikely
> > > approach, this is impossible, as without parsing you won't know
> where the
> > list
> > > finishes.  If you do do your own parse, you can populate your
> > datastructures
> > > directly during the parse, and what list separator was originally
> used in
> > the
> > > data file is completely irrelevant.
> > >
> > > Re complexity: not sure how you are planning to deal with
> whitespace in
> > the
> > > formal grammar, but consider the following, where I have assumed
> that each
> > > token 'eats up' the following whitespace.
> > >
> > > <dataitem> = <dataname><whitespace>+<datavalue>
> > > <datavalue> = {<list>|<string>}<whitespace>+
> > > <listdatavalue> = {<list>|<string>}<whitespace>*
> > > <list> = '[' <whitespace>* {<listdatavalue>
> > > {<comma><whitespace>*<listdatavalue>}*}* ']'
> > >
> > > If we make comma or whitespace possible separators, the last
> production
> > > becomes:
> > > <list> =  '[' <whitespace>* {<listdatavalue> {<comma or
> > > whitespace><listdatavalue>}*}* ']'
> > >
> > > This looks like no extra complexity, and from a user's point of
> view
> > > whitespace as an alternative separator is simple to understand and
> > consistent
> > > with space as a token separator used everywhere else in CIF. 
> Anyway, if
> > > reduction of grammar complexity is your goal, you can just
> completely
> > exclude
> > > commas as list separators!
> >
> > Why not? Make them spaces only, and you become consistent across the
> board.
> > I have to think about the possibility of pathological cases where
> spaces
> > won't work. I can't think of any at the moment.
> >
> > >
> > > Some questions about how commas behave:
> > > 1: is a trailing comma e.g. [1,2,3,4,] a syntax error?
> > > 2. are two commas in a row a syntax error? E.g. [1,2,3,,4]
> >
> > I would say yes to syntax error. I an easily determine they may need
> to be
> > an additional list value, but can't determine what.
> >
> > > Note the above productions assume that the answer to both is yes.
> > >
> > >>
> > >> What big advantage to a language is there to specify you can use
> a comma
> > or
> > >> whitespace as a token separator? Will you be happy with the first
> person
> > who
> > >> interprets this as being ok
> > >>
> > >> loop_
> > >>   _severalvalues 1,2,3,4,5,6,7 # these being the 7 values of
> > severalvalues
> > >>
> > > Note sure what you are getting at here: I am proposing the
> following:
> > >
> > > _nicelist      [1 2 3 4 5 6 7]
> > >
> > > being the same as
> > >
> > > _nicelist      [1,2,3,4,5,6,7]
> > >
> > >  Don't see how this relates to loops.
> >
> > The point was, once you say a space and comma are equivalent token
> > separators then will it be an interpretation that they are always so
> even in
> > loops? My example was not a list, just 7 values that were separated
> by
> > commas not spaces.
> >
> > >
> > > James.
> > > ------
> > >>
> > >> On 27/11/09 11:41 AM, "James Hester" <jamesrhester@gmail.com
> > >> <http://jamesrhester@gmail.com> > wrote:
> > >>
> > >>> Dear All: looking over the list I posted previously of items
> left to
> > >>> resolve, I see only one serious one outstanding: whether or not
> to allow
> > >>> space as a separator between list items.  Nick has stated:
> > >>>
> > >>> " I will propose it has to be a comma, but make the coercion
> rule that
> > space
> > >>> separated values in a list-type object be coerced into comma
> separated
> > >>> values. That is, read spaces as you want, but don't encourage
> them."
> > >>>
> > >>> I would like to counter-propose, as Joe did originally, that
> whitespace
> > be
> > >>> elevated to equal status with comma as a valid list separator. 
> I see no
> > >>> downside to this.  Would anyone else like to speak to this issue
> before
> > we
> > >>> vote?  In particular, I would be interested to hear why Nick
> doesn't
> > want to
> > >>> encourage spaces.
> > >>
> > >> cheers
> > >>
> > >> Nick
> > >>
> > >> --------------------------------
> > >> Associate Professor N. Spadaccini, PhD
> > >> School of Computer Science & Software Engineering
> > >>
> > >> The University of Western Australia    t: +61 (0)8 6488 3452
> > >> 35 Stirling Highway                    f: +61 (0)8 6488 1089
> > >> CRAWLEY, Perth,  WA  6009 AUSTRALIA   w3:
> www.csse.uwa.edu.au/~nick
> > >> <http://www.csse.uwa.edu.au/%7Enick>
> > >> MBDP  M002
> > >>
> > >> CRICOS Provider Code: 00126G
> > >>
> > >> e: Nick.Spadaccini@uwa.edu.au <http://Nick.Spadaccini@uwa.edu.au>
> > >>
> > >>
> > >>
> > >> _______________________________________________
> > >> ddlm-group mailing list
> > >> ddlm-group@iucr.org
> > >> http://scripts.iucr.org/mailman/listinfo/ddlm-group
> > >>
> > >
> > >
> >
> > cheers
> >
> > Nick
> >
> > --------------------------------
> > Associate Professor N. Spadaccini, PhD
> > School of Computer Science & Software Engineering
> >
> > The University of Western Australia    t: +61 (0)8 6488 3452
> > 35 Stirling Highway                    f: +61 (0)8 6488 1089
> > CRAWLEY, Perth,  WA  6009 AUSTRALIA  w3: www.csse.uwa.edu.au/~nick
> > MBDP  M002
> >
> > CRICOS Provider Code: 00126G
> >
> > e: Nick.Spadaccini@uwa.edu.au
> >
> >
> >
> >
> > _______________________________________________
> > ddlm-group mailing list
> > ddlm-group@iucr.org
> > http://scripts.iucr.org/mailman/listinfo/ddlm-group
> >
> >
> 
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