| Time |
Nick |
Message |
| 23:07 |
jdurand |
ronsavage: Heu... no - tell me more |
| 00:02 |
ronsavage |
JavaScript: The Good Parts is just 150 pages, with discussions of some of the bad parts of JS. The author's attitude is that there are many appalling design decisions baked into the syntax. He recommends therefore a smallish subset to use in reliable code. Appendix A is Awful Parts. Appendix B is Bad Parts. Appendix C is JSLint. Appendix D is syntax in railroad form. Appendix E is JSON in railroad form incl. a JSON parser in JS. |
| 00:05 |
jdurand |
ronsavage: ah! Many thanks! |
| 00:21 |
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jeffreykegler joined #marpa |
| 05:11 |
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ilbot3 joined #marpa |
| 05:11 |
|
Topic for #marpa is now Current release: https://metacpan.org/pod/Marpa::R2 Source: https://github.com/jeffreykegler/Marpa--R2 public logs at http://irclog.perlgeek.de/marpa/today |
| 05:35 |
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jeffreykegler joined #marpa |
| 05:36 |
jeffreykegler |
A quick report on Phase 3: |
| 05:36 |
jeffreykegler |
It's going very smoothly, if a bit slowly. |
| 05:37 |
jeffreykegler |
In the aftermath of the removal of the LR(0) states, a lot of code is now unnecessary, and is being removed as I go. |
| 05:37 |
jeffreykegler |
For example, one full pass over the entire bocage during its construction was for the removal of duplicates, something which now cannot occur. |
| 05:38 |
jeffreykegler |
I've just removed that pass. Libmarpa is getting smaller and simpler, while adding features. |
| 05:39 |
jeffreykegler |
Anyway, if there is pressure to do an interpass, I can interrupt Phase 3 at pretty much any point. |
| 05:41 |
jeffreykegler |
In Phases 1 and 2, it was like having a motorcycle in pieces on the living room floor -- you can't just take it off the race course at a moment's notice. |
| 05:42 |
jeffreykegler |
Phase 3 is more like I'm polishing the chrome, or maybe changing a spark plug. |
| 05:42 |
jeffreykegler |
Good night! |
| 05:48 |
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jeffreykegler joined #marpa |
| 05:49 |
jeffreykegler |
* "take it off the race course" -> "take it out on the race course" |
| 06:25 |
ronsavage |
jeffreykegler: This sort of progress must be very pleasing |
| 06:28 |
ronsavage |
Off topic: After another fight with BerkeleyDB (http://savage.net.au/Ron/html/Oracle.and.Perl.BerkeleyDB.html) I've manged to install all my modules under Perl V 5.18.2 (which I switched to a couple of days ago) |
| 10:14 |
* jdurand |
is now entering test phase of the Marpa-powered JavaScript regexp |
| 12:46 |
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jdurand joined #marpa |
| 17:15 |
jdurand |
Jeffrey, there is no way to pass arguments to a semantics_package's new() except by localizing variables, is that correct? |
| 19:02 |
|
jeffreykegler joined #marpa |
| 19:04 |
jeffreykegler |
judrand: re http://irclog.perlgeek.de/marpa/2014-02-02#i_8213714 -- The per-parse argument is passed using the $slr->value() method: https://metacpan.org/pod/release/JKEGL/Marpa-R2-2.078000/pod/Scanless/R.pod#value |
| 19:07 |
jdurand |
ok - thx |
| 22:11 |
jdurand |
FYI the tests with the JavaScript regexp engine are doing well, minor bug fixes on the way |
| 22:15 |
jdurand |
Question about actions: it seems that if I say action => XXX and XXX cannot be resolved, Marpa does not yell and ignores it - is that an expected behaviour ? |
| 22:23 |
|
jeffreykegler joined #marpa |
| 22:25 |
jeffreykegler |
jdurand: re http://irclog.perlgeek.de/marpa/2014-02-02#i_8214702 -- An action which cannot be resolved should be a fatal error. If Marpa is silently ignoring a resolution failure, that is a bug. Can you create a test case? |
| 22:33 |
jdurand |
Yep - otherwise big success with the Marpa-powered JavaScript Regexp Engine -; ! |
| 22:33 |
jeffreykegler |
judrand: Glad to hear it. |
| 22:39 |
jdurand |
issue created |
| 22:41 |
jdurand |
Yes, I am very happy, because this was really tedious work, and very glad to have perl in my hands since doing a user-land regular expression engine required closures calling closues callsing closures etc... A very dynamic clode |
| 22:41 |
jdurand |
"code" |
| 22:41 |
jdurand |
The JavaScript regexp is pecular: it has adopted a subset of perl from grammar point of view, but the semantics are different |
| 22:41 |
jeffreykegler |
judrand: Are you thinking of blogging this? |
| 22:42 |
jdurand |
I was - the only "problem", if it is, is that it is inside the bigger package MarpaX::Languages::ECMAScript::AST |
| 22:42 |
jdurand |
and not a package of its own |
| 22:43 |
jdurand |
but if that is not a problem for you, well it is not for me |
| 22:43 |
jdurand |
neither |
| 22:43 |
jeffreykegler |
jdurand: I don't see a problem. |
| 22:44 |
jeffreykegler |
It would introduce people to MarpaX::Languages::ECMAScript::AST through a subset of its capabilities. |
| 22:44 |
jdurand |
ok, blogs.perl.org then - I finish the test suite, c.f. https://github.com/jddurand/MarpaX-Languages-ECMAScript-AST/blob/master/t/pattern.t just to be sure I am hitting all the actions writen, and can blog about it |
| 22:45 |
jdurand |
The "data" is in the %DATA hash of this file |
| 22:45 |
jdurand |
Ah yes, very important... |
| 22:45 |
jeffreykegler |
A lot of people learn things best via subsets they already understand ... |
| 22:45 |
jdurand |
I could have "fake" JavaScript regular expression by using perl regexp in my actions right |
| 22:45 |
jeffreykegler |
and the Perl audience easily relates to regexes. |
| 22:46 |
jdurand |
so I made sure I do not fall into this plagiat - yes, you are right, this will be a good advertising of Marpa and its capabilities |
| 22:46 |
jdurand |
in fact I can gaurantee that I could have never writen that without it |
| 22:47 |
jeffreykegler |
very nice |
| 22:48 |
jdurand |
this is very tricky... the final value returned by Marpa is a CODE reference that is a "live" engine created using closures through all the actions of the Regular Expression grammar |
| 22:49 |
jdurand |
Sometimes some actions are returning closures that contain themselve closures ! |
| 22:49 |
jeffreykegler |
very trendy :-) |
| 22:50 |
jdurand |
For the curious the grammar is in the __DATA__ section of https://github.com/jddurand/MarpaX-Languages-ECMAScript-AST/blob/master/lib/MarpaX/Languages/ECMAScript/AST/Grammar/ECMAScript_262_5/Pattern.pm |
| 22:50 |
jdurand |
nothing particular with it - quite a simple BNF stuff in fact |
| 22:50 |
jdurand |
but the actions... ouh ouh....! |
| 22:50 |
jdurand |
https://github.com/jddurand/MarpaX-Languages-ECMAScript-AST/blob/master/lib/MarpaX/Languages/ECMAScript/AST/Grammar/ECMAScript_262_5/Pattern/DefaultSemanticsPackage.pm |
| 22:51 |
jeffreykegler |
You could have done it using recursive descent, and then your parser would be just as complicated and large as your semantics :-) |
| 22:52 |
jdurand |
hmmmm why not |
| 22:52 |
jdurand |
.... lol! [smiles] -; |
| 22:53 |
jeffreykegler |
Not only that, but the two would be tangled together is a very impressive way. :-) |
| 22:55 |
jdurand |
yep - anyway, that is a major step in my work for the full JavaScript Runtime Engine - |
| 22:55 |
jdurand |
First I naively though to use perl regexps in the background... but not, JavaScript has the remarquable attribute that it looks like X but is not X |
| 22:56 |
jdurand |
where X is a mixture of Perl, C, in particular |
| 22:56 |
jdurand |
and actions returning closures that call themselves recursively is quite impressive |
| 22:57 |
jeffreykegler |
For some things, the Marpa-powered regexes might work better than the native ones -- particularly cases involving ambiguity or where the regex engines have to backtrack a lot. |
| 23:00 |
jdurand |
Sure I understand that - and what is nice is that it is userland - so every modif can be tested very easily |
| 23:01 |
jdurand |
Btw, when I started, it was friday evening, I was thinkg to do that in XS maybe, and, luckily (!?) I decided no because |
| 23:01 |
jdurand |
ahemmm... |
| 23:01 |
jdurand |
there is no way to do closures in C without having to deal explicitely with stack operations in our code isn't it? |
| 23:02 |
jeffreykegler |
... you can do Perl closures from C, and earlier versions of Marpa did. |
| 23:03 |
jeffreykegler |
But it makes catching errors harder, and raises a lot of tricky issues. |
| 23:03 |
jeffreykegler |
For example, have you noted the controversy about fatal warnings now in the Perl blogosphere? |
| 23:03 |
jdurand |
Yes, the XS way via perl - I understand that - your experience in that says me it is good I have not done it like this |
| 23:04 |
jdurand |
I have seen that in blogs, yes |
| 23:04 |
jeffreykegler |
Now, just to be clear, I am *not* addressing that controversy itself -- I'll stay out of it, but ... |
| 23:04 |
jdurand |
Understood - but it worried me because I systematically using warnings FATAL => 'ALL' |
| 23:05 |
jeffreykegler |
Consider callbacks. What do you do about warnings in the Perl code you are calling back from C? |
| 23:05 |
jdurand |
Damned... that's a good question |
| 23:05 |
jeffreykegler |
Do you silently throw away warnings in Perl callbacks? |
| 23:06 |
jeffreykegler |
Or do you make them fatal? (Again emphasizing I am *not* addressing the general case discussed in the blog pieces.) |
| 23:06 |
jeffreykegler |
Either of these has extreme disadvantages. |
| 23:07 |
jdurand |
Yes - understood |
| 23:07 |
jeffreykegler |
A third way is to set up a kind of event mechanism to transmit the warning from Perl through C, and then report it in Perl. |
| 23:07 |
jeffreykegler |
And that is just one issue with callbacks. |
| 23:08 |
jeffreykegler |
So Marpa no longer uses Perl callbacks from C -- I switched to doing via an event mechanism, which directs the outer Perl layer to make the call. |
| 23:08 |
jeffreykegler |
That way I always have Perl calling Perl, and the issues become much easier. |
| 23:08 |
jdurand |
Non trivial issues, almost philosophical, I have not read blogs since a day and a hlaf maybe I should to keep uptodate on this subject - I guess you took the correct decision |
| 23:09 |
jdurand |
in the sense that within one framework this is managable, where framework mean the runtime engine |
| 23:09 |
jeffreykegler |
I looked at a lot of other Perl modules, and almost universally they callback Perl from XS in similar cases. |
| 23:09 |
jdurand |
and I mean here that the perl runtime engine is not the same thing as an XS below |
| 23:10 |
jeffreykegler |
And I implemented it that way originally in Marpa. |
| 23:10 |
jeffreykegler |
But I think event-driven really is the better way. |
| 23:13 |
jdurand |
You have biggger experience than me on that subject - clearly |
| 23:14 |
jdurand |
ok, it is a bit late here in west Europe, and have to sleep a while - many thanks for your support |
| 23:14 |
jdurand |
and yes, I will blog about it |
| 23:14 |
jeffreykegler |
Great! A good night to you! |
| 23:14 |
jdurand |
and I have not forgotten I have to write a test case for the lexeme stuff |
| 23:14 |
jdurand |
-; |
| 23:14 |
jdurand |
good night |
| 23:25 |
ronsavage |
jdurand: What is the word 'plagiat' that you used? |
| 23:30 |
jeffreykegler |
ronsavage: it's French ("No kidding, Sherlock"), related to our word plagiarism, but I think in French it also has a sense similar to the way we use "borrow". |
| 23:32 |
jeffreykegler |
jdurand was (I think) referring to having considered simply being a very thin layer over Perl regexes, in effect, simply borrowing his semantics from them. |
