support for SLIF extensions

[rns]

This is a tracker issue to list discuss LUIF support for extensions proposed to Marpa::R2 SLIF.

Some possible sources:

https://github.com/jeffreykegler/Marpa--R2/blob/master/plans/TODO.pod

[jeffreykegler]

Would you bring the topic of separators up on the IRC channel? I'll chime in to confirm the importance of the discussion in my eyes.

As for the rest, we can deal with them later. I anticipate a discussion phase once we have a good draft of the LUIF manual as its basis.

[rns]

Question about separators on IRC -- http://irclog.perlgeek.de/marpa/2015-05-03#i_10538440

[rns]

One such "shoot yourself in the foot" extension to SLIF would be regexes instead of character classes -- these would remove the need to write an external lexer in many cases.

Regexes can be passed through to the host language as is currently done with charclasses and Perl in Marpa::R2.

[rns]

Opinions on sequence separators from IRC channel

Lukas Atkinson (lwa) -- http://irclog.perlgeek.de/marpa/2015-05-03#i_10539019
ceridwen -- http://irclog.perlgeek.de/marpa/2015-05-03#i_10539597
ronsavage -- http://irclog.perlgeek.de/marpa/2015-05-03#i_10541463

[rns]

character classes added as sequence separators 4298a60