Re: A5: a few simple questions
David Whipp wrote:
First, a slight clarification: if I say:
m:w/ %foo := [ (\w+) = (\w+) [ , (\w+) ]* ] /
does this give me a hash of arrays? (i.e. is the rhs of a hash processed as
a scalar context)
That's an error. The grouping bound to a hypothetical hash has to have
either exactly one or exactly two captures in it. To get what you want
you'd need something like:
rule wordlist { (\w+) [ , (\w+) ]* }
m:w/ %foo := [ (\w+) = (wordlist) ] /
or just:
m:w/ %foo := [ (\w+) = ({ /(\w+) [ , (\w+) ]*/ }) ] /
When I look at this, I see a common pattern: the join/split concept. It
feels like there should be a standard assertion:
These are good ideas for assertions. If they don't become standard, it will
certainly be possible to write a module that makes them available.
And a question about m,n (I think something similar came up a few weeks
ago): why isn't it m..n, i.e. a list of the numbers of matches allowed.
This seems to be the only place in perl6 where a list of numbers, as a
range, isn't constructed using the .. operator.
Because a m,n isn't a list of numbers. It's the lower and upper bounds on a
repetition count.
Damian
Re: A5: a few simple questions
On 6/6/02 2:43 AM, Damian Conway wrote:
rule wordlist { (\w+) [ , (\w+) ]* }
No semicolon at the end of that line? I've already forgotten the new
rules for that type of thing... :)
-John
Re: A5: a few simple questions
On Thu, Jun 06, 2002 at 10:38:39AM -0400, John Siracusa wrote:
On 6/6/02 2:43 AM, Damian Conway wrote:
rule wordlist { (\w+) [ , (\w+) ]* }
No semicolon at the end of that line? I've already forgotten the new
rules for that type of thing... :)
No, because rules are basically methods, just like grammars are
basically classes. You would only need a semi-colon if you were defining
an anonymous Crule (similar to an anonymous Csub):
my $wordlist = rule { (\w+) [ , (\w+) ]* };
Allison
Re: A5: a few simple questions
Allison Randal [EMAIL PROTECTED] writes:
On Thu, Jun 06, 2002 at 10:38:39AM -0400, John Siracusa wrote:
On 6/6/02 2:43 AM, Damian Conway wrote:
rule wordlist { (\w+) [ , (\w+) ]* }
No semicolon at the end of that line? I've already forgotten the new
rules for that type of thing... :)
No, because rules are basically methods, just like grammars are
basically classes. You would only need a semi-colon if you were defining
an anonymous Crule (similar to an anonymous Csub):
my $wordlist = rule { (\w+) [ , (\w+) ]* };
You wouldn't even need it then. Assuming you're following the closing
brace with nothing but white space and a newline.
--
Piers
It is a truth universally acknowledged that a language in
possession of a rich syntax must be in need of a rewrite.
-- Jane Austen?
Re: A5: a few simple questions
On Thu, Jun 06, 2002 at 08:21:25PM +0100, Piers Cawley wrote:
Allison Randal [EMAIL PROTECTED] writes:
No, because rules are basically methods, just like grammars are
basically classes. You would only need a semi-colon if you were defining
an anonymous Crule (similar to an anonymous Csub):
my $wordlist = rule { (\w+) [ , (\w+) ]* };
You wouldn't even need it then. Assuming you're following the closing
brace with nothing but white space and a newline.
I guess you're talking about the bit of A4 to do with When do I put a
semicolon after a curly?. But that is if the final curly is on a line
by itself. So you could get away with:
my $wordlist = rule {
(\w+) [ , (\w+) ]*
}
Allison
A5: a few simple questions
First, a slight clarification: if I say:
m:w/ %foo := [ (\w+) = (\w+) [ , (\w+) ]* ] /
does this give me a hash of arrays? (i.e. is the rhs of a hash processed as
a scalar context)
When I look at this, I see a common pattern: the join/split concept. It
feels like there should be a standard assertion:
m:w/ %foo := [ (\w+) = split , (w+) ] /
..
Another useful assertion might the the long form of m,n repeat count:
m:w/ list := (\w+) repeat grep { even } 0..Inf ] /
to match an even number of words.
And a question about m,n (I think something similar came up a few weeks
ago): why isn't it m..n, i.e. a list of the numbers of matches allowed.
This seems to be the only place in perl6 where a list of numbers, as a
range, isn't constructed using the .. operator.
Dave.
--
Dave Whipp, Senior Verification Engineer,
Fast-Chip inc., 950 Kifer Rd, Sunnyvale, CA. 94086
tel: 408 523 8071; http://www.fast-chip.com
Opinions my own; statements of fact may be in error.
