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Re: comprehensive list of perl6 rule tokens

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From:
Jeff 'japhy' Pinyan
Date:
May 24, 2005 20:25
Subject:
Re: comprehensive list of perl6 rule tokens
Message ID:
Pine.LNX.4.61.0505242315510.14648@perlmonk.org
On May 24, Jonathan Scott Duff said:

> On Tue, May 24, 2005 at 08:25:03PM -0400, Jeff 'japhy' Pinyan wrote:
>>   http://japhy.perlmonk.org/perl6/rules.txt
>
> That looks completish to me.  (At least I didn't think, "hey! where's
> such and such?")

Oh, frabjous day!

> One thing that I noticed and had to look up was
>
> 	<-prop X>
>
> though.  Because ...

I wish <!prop X> was allowed.  I don't see why <!...> has to be confined 
to zero-width assertions.

>> The part which needs a bit of clarification right now, in my opinion, is
>> character classes.  From what I can gather, these are character classes:
>>
>>   <[a-z] +<digit>>
>>   <+<alpha> -[aeiouAEIOU]>
>
> I believe that Larry blessed Pm's idea to allow
>
> 	<[a..z]+digit>
> 	<+alpha-[aeiouAEIOU]>

Ok, that's news to me.  (I have yet to peruse the archives.)  That's nice, 
not requiring you to <>-ize property names inside a character class 
assertion.  I'd think whitespace would be permitted in between parts of a 
character class, but perhaps I'm wrong.  That would kinda go against the 
whole "whitespace for readability" idea of Perl 6 rules, though.

> which implies to me that assertions starting with one of "<[",
> "<-" or "<+" should be treated as character classes.  This doesn't
> seem to play well with <-prop X>.  Maybe it does though.

Considering the Unicode properties are like char class macro-things (like 
\w and \d), I don't see a problem, except for the fact that there's more 
than one "word" (chunk of non-whitespace) associated with them.  Maybe 
Unicode properties retain their enclosing <>'s?

> Also, I think that it's [a..z] now rather than [a-z] but I'm not
> entirely sure.  At least that's how PGE implements it.

Ok.  I'll wait for a message from On High about that.  It's a minor 
detail.

>> but I want to be sure.  I'm also curious about whitespace.  Is "<[" one
>> token, or can I write "< [a-z] >" and have it be a character class?
>
> I think you need to write "<["

I expected as much.

-- 
Jeff "japhy" Pinyan         %  How can we ever be the sold short or
RPI Acacia Brother #734     %  the cheated, we who for every service
http://japhy.perlmonk.org/  %  have long ago been overpaid?
http://www.perlmonks.org/   %    -- Meister Eckhart

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