Perl 6 - the future is here, just unevenly distributed

IRC log for #marpa, 2017-05-29

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All times shown according to UTC.

Time Nick Message
00:13 idiosyncrat joined #marpa
00:53 idiosyncrat Demat!
01:48 ilbot3 joined #marpa
01:48 Topic for #marpa is now Start here: http://savage.net.au/Marpa.html - Code paste/run: https://f.perlbot.pl/#marpa - Jeffrey's Marpa site: http://jeffreykegler.github.io/Marpa-web-site/ - IRC log: http://irclog.perlgeek.de/marpa/today - Youtube channel: https://www.youtube.com/channel/UCYKVfGBtfTqbs1JdYq-dc5g
06:01 ronsavage joined #marpa
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17:30 jdurand joined #marpa
17:33 jdurand Hello! At the libmarpa level, suppose that we define a sequence rule with a separator symbol that is also a sequence. Supposing that this would be possible in Marpa::R2, I'd write it like this: rule ::= member* separator => sep; sep => 'x'+
17:34 jdurand - what is the semantic for separator ?
17:35 jdurand it seems to me that this is working ok, i.e. I can have 'x' as many times as wanted between every member. I was wondering if this is a fortunate side-effect or it that is exactly what is expected -;
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22:46 idiosyncrat jdurand: re https://irclog.perlgeek.de/marpa/2017-05-29#i_14654329
22:46 idiosyncrat The behavior described is as intended.
22:47 idiosyncrat http://search.cpan.org/~jkegl/Marpa-R2-3.000000/pod/Scanless/DSL.pod#separator
22:48 idiosyncrat The separator must be a single symbol, but it may be a LHS which means indirectly it could be anything.  One restriction is enforced --
22:49 idiosyncrat Whatever (sub)grammar the separator represents cannot be nullable.  This is because if you get into "invisible" separators, things get out of hand, so much so that it's usually a sign of a user error.
22:51 idiosyncrat Users who really want optional separators can specify this directly in BNF -- this forces them to spell out what they really want, which is (I think) a good thing.
22:54 idiosyncrat Except for being a bit of a "nanny" re nullables, my intent was to be totally unrestrictive.
23:32 ronsavage joined #marpa

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