Perl 6 - the future is here, just unevenly distributed

IRC log for #marpa, 2015-09-05

| Channels | #marpa index | Today | | Search | Google Search | Plain-Text | summary

All times shown according to UTC.

Time Nick Message
00:17 idiosyncrat_ joined #marpa
00:25 idiosyncrat_ Here's my email to the Google group on why I eliminated the LR(0) states from the Marpa parse engine
00:26 idiosyncrat_ https://groups.google.com/forum/#!s​earchin/marpa-parser/LR%280%29/marp​a-parser/Nmem6JCes-A/O7blJqwaDRMJ
00:32 idiosyncrat_ Re theory paper vs. Kollos
00:33 idiosyncrat_ From the first day of my work on the new Marpa, 8 years ago, I envisioned a two-pronged effort --
00:33 idiosyncrat_ Implementation *and* theory
00:35 idiosyncrat_ Usually people did one or the other -- with yacc, Johnson wrote it and three people did the theory
00:35 idiosyncrat_ Knuth invented LR, de Remer invented LALR, and Aho advised Johnson on the theory.
00:36 idiosyncrat_ Based on the fate of Joop Leo's paper, I realized I would have to do it all, or the effort might well come to nothing.
00:37 idiosyncrat_ I realized that parsing had fallen severely out of fashion, and never considered wasting time applying for funding, etc.
00:37 idiosyncrat_ Anyway, I do back and forth, depending on the interest shown.
00:38 idiosyncrat_ I tended to assume that the theory side was necessary, but success would come from the practitioners -- programmers who realized Marpa did what they needed done, and what the traditional algorithm did not do.
00:39 idiosyncrat_ I thought the practitioners would lead the academics, and so far that has been the case.
00:39 idiosyncrat_ Anyway, it turns out that some people are actually reading my paper carefully at this point.
00:41 idiosyncrat_ It had needed revisions, but I didn't want to prioritize these unless I felt there were some readers out there to be benefited.
00:42 idiosyncrat_ Because I know that there are folks waiting to use Kollos, when we finish it.
03:28 idiosyncrat_ joined #marpa
05:43 koo7 joined #marpa
06:48 pczarn joined #marpa
09:00 lwa joined #marpa
15:29 ceridwen joined #marpa
15:29 ceridwen joined #marpa
16:29 MerittClarksdale joined #marpa
16:47 MerittClarksdale Greetings
16:59 idiosyncrat joined #marpa
16:59 MerittClarksdale hi
17:00 idiosyncrat hi
17:27 MerittClarksdale is marpa both a lexer and parser?
17:28 idiosyncrat The algorithm technically is a parser
17:28 idiosyncrat But Marpa::R2's SLIF interface includes a lexer.
17:29 idiosyncrat So from the point of view of somebody just getting into it via Marpa::R2, it is both.
17:31 MerittClarksdale Its often seemed to me the main difference between lexers and parsers is lexers tend to analyse characters, and mainly just demarcate them and tag them to make a token, but a parser looks at tokens and has to reorganize and reorder the data, but otherwise algorithms are similar
17:32 MerittClarksdale Parsers seem to be somewhat like XSLT to me
17:32 idiosyncrat Right
17:33 idiosyncrat In fact, in the SLIF, Marpa is also used to do the lexing, which is kind of overkill
17:34 idiosyncrat Traditionally, for language parsing, you have two layers -- folks who have used yacc/bison will have encountered this.
17:34 idiosyncrat yacc does not do lexing and requires you to have an entire separate phase.
17:35 idiosyncrat You can also use Marpa::R2 and its SLIF, with a separate lexer, if you prefer
17:36 MerittClarksdale yes
17:50 MerittClarksdale Earley can be used as a lexer?
17:59 idiosyncrat Any sufficiently powerful parser can be used as a lexer.
17:59 idiosyncrat In theory you could use yacc's LALR for lexing.
18:00 idiosyncrat You just have to have a parser inventor who is crazy enough to also use his algorithm as a lexer.
18:00 idiosyncrat I think I'm the first one. :-)
18:01 idiosyncrat Earley is overkill for a lexer, but the implementation is in C, and it is usually competing with alternatives in Perl.
18:02 idiosyncrat And there are some advantages to power in lexing -- your tokens do not have to be regular expressions, and handling ambiguity and non-determinism at the lexer level all of sudden becomes quite easy.
18:05 MerittClarksdale right
20:13 koo7 joined #marpa

| Channels | #marpa index | Today | | Search | Google Search | Plain-Text | summary