A Perl 6 developer’s reply to a Russian Perl Podcast

[This is a response to the Russian Perl Podcast transcribed by Peter Rabbitson and discussed at blogs.perl.org.]

I found this translation and podcast to be interesting and useful, thanks to all who put it together.

Since there seems to have been some disappointment that Perl 6 developers didn’t join in the discussions about “Perl 7″ earlier this year, and in the podcast I’m specifically mentioned by name, I thought I’d go ahead and comment now and try to improve the record a bit.

While I can’t speak for the other Perl 6 developers, in my case I didn’t contribute to the discussion because nearly all the things I would’ve said were already being said better by others such as Larry, rjbs, mst, chromatic, etc.  I think a “Perl 7″ rebrand is the wrong approach, for exactly the reasons they give.

A couple of statements  in the podcast refer to “hurting the feelings of Perl 6 developers” as being a problem resulting from a rebrand to Perl 7. I greatly appreciate that people are concerned with the possible impact of a Perl 5 rebrand on Perl 6 developers and our progress.  I believe that Perl 6′s success or failure at this point will have little to do with the fact that “6 is larger than 5″.  I don’t find the basic notion of “Perl 7″ offensive or directly threatening to Perl 6.

But I fully agree with mst that “you can’t … have two successive numbers in two brands and not expect people to be confused.”  We already have problems explaining “5″ and “6″ — adding more small integers to the explanation would just make an existing problem even worse, and wouldn’t do anything to address the fundamental problems Perl 6 was intended to resolve.

Since respected voices in the community were already saying the things I thought about the name “Perl 7″, I felt that adding my voice to that chorus could only be more distracting than helpful to the discussion. My involvement would inject speculations on the motivations of Perl 6 developers into what is properly a discussion about how to promote progress with Perl 5.  I suspect that other Perl 6 developers independently arrived at similar conclusions and kept silent as well (Larry being a notable exception).

I’d also like to remark on a couple of @sharifulin’s comments in the podcast (acknowledging that the transcribed comments may be imprecise in the translation from Russian):

First, I’m absolutely not the “sole developer” of Perl 6 (13:23 in the podcast), or even the sole developer of Rakudo Perl 6.  Frankly I think it’s hugely disrespectful to so flippantly ignore the contributions of others in the Perl 6 development community.  Let’s put some actual facts into this discussion… in the past twelve months there have been over 6,500 commits from over 70 committers to the various Perl 6 related repositories (excluding module repositories), less than 4% (218) of those commits are from me. Take a look at the author lists from the Perl 6 commit logs and you may be a little surprised at some of the people you find listed there.

Second, there is not any sense in which I think that clicking ”Like” on a Facebook posting could be considered “admitting defeat” (13:39 in the podcast). For one, my “Like” was actually liking rjbs’ reply to mst’s proposal, as correctly noted in the footnotes (thanks Peter!).

But more importantly, I just don’t believe that Perl 5 and Perl 6 are in a battle that requires there to be a conquerer, a vanquished, or an admission of defeat.


Posted in perl6, rakudo | 1 Comment

A Rakudo Performance

At YAPC::NA 2012 in Madison, WI I gave a lightning talk about basic improvements in Rakudo’s performance over the past couple of years.  Earlier today the video of the lightning talks session appeared on YouTube; I’ve clipped out my talk from the session into a separate video below.  Enjoy!


Posted in perl6, rakudo | 5 Comments

Roborama 2012a

A couple of weeks ago I entered the Dallas Personal Robotics Group Roborama 2012a competition, and managed to come away with first place in the RoboColumbus event and Line Following event (Senior Level).  For my robot I used one of the LEGO Mindstorms sets that we’ve been acquiring for use by our First Lego League team, along with various 3rd party sensors.

The goal of the RoboColumbus event was to build a robot that could navigate from a starting point to an ending point placed as far apart as possible; robots are scored on distance to the target when the robot stops.  If multiple robots touch the finish marker (i.e., distance zero), then the time needed to complete the course determines the rankings.   This year’s event was in a long hall with the target marked by an orange traffic cone.

HiTechnic IR ball and IRSeeker

HiTechnic IR ball and IRSeeker sensor

Contestants are allowed to make minor modifications to the course to aid navigation, so I equipped my robot with a HiTechnic IRSeeker sensor and put an infrared (IR) electronic ball on top of the traffic cone.  The IRSeeker sensor reports the relative direction to the ball (in multiples of 30 degrees), so the robot simply traveled forward until the sensor picked up the IR signal, then used the IR to home in on the traffic cone.  You can see the results of the winning run in the video below, especially around the 0:33 mark when the robot makes its first significant IR correction:


My first two runs of RoboColumbus didn’t do nearly as well; the robot kept curving to the right for a variety of reasons, and so it never got a lock on the IR ball.  Some quick program changes at the contest and adjustments to the starting direction finally made for the winning run.

For the Line Following contest, the course consisted of white vinyl tiles with electrical tape in various patterns, including line gaps and sharp angles.  I used a LineLeader sensor from mindsensors.com for basic line following, with some heuristics for handling the gap conditions.  The robot performed fine on my test tiles at home, but had difficulty with the “gap S curve” tiles used at the contest.  However, my robot was the only one that successfully navigated the right angle turns, so I still ended up with first place.  :-)

Matthew and Anthony from our FLL robotics team also won other events in the contest, and there are more videos and photos available.  The contest was a huge amount of fun and I’m already working on new robot designs for the next competition.

Many thanks to DPRG and the contest sponsors for putting on a great competition!


Posted in lego, robotics | Tagged , | 1 Comment

Oslo Perl 6 Patterns Hackathon, Days 1-2

For the past couple of days I’ve been in Oslo, Norway, attending the Perl 6 Patterns Hackathon sponsored by Oslo Perl Mongers, Jan Ingvoldstad IT, and NUUG Foundation. A lot of things are happening at the hackathon, as you’ll see below.

First, Oslo itself is every bit as nice as I remember from attending the Nordic Perl Workshop in 2009 (and another hackathon that took place then). And once again, the hackathon organizers (Jan, Karl, Salve) — have done an amazing job in making sure that all of us at this hackathon can remain productive at working on Perl 6 as well as having a good time while we’re here. The food, facilities, and hospitality have been outstanding.

moritz++ and jnthn++ have already blogged about their work thus far at the hackathon; here are a few other things that have taken place while we’re here:

* Friday morning I noticed in the latest Rakudo compiler release notes that autovivification of hashes and arrays still wasn’t fully implemented in the nom version of Rakudo. So, I spent a bit of time early Friday confirming with jnthn++ and masak++ about some autovivification edge cases, and then implemented the rest of what we need from autoviv. So, that’s an important feature restored.

* jnthn++ worked on getting the :i (:ignorecase) flag working for interpolated literals in regexes; I helped a bit with that, but in the process noticed just how bad things were for people who had Parrot compiled without ICU. There were lots of failing spec tests and problems with doing case-insensitive regexes matches, even for simple strings. The crux of the problem was that Parrot simply threw exceptions for case conversions of several Unicode encodings whenver ICU was present, even if the strings involved had only ASCII or Latin-1 characters.  I noticed that this problem affected several of the people attending the hackathon today (including jnthn++), so I decided it could not be allowed to live.  So, I added a patch to Parrot that enables more case conversions when ICU isn’t present, as long as all of the codepoints involved are in ASCII or Latin-1 (which the majority of them are). If ICU is present, Parrot continues to use ICU, but if ICU isn’t available, Parrot is at least able to handle case conversions for most of the strings we encounter.

* We had a lot of relative newcomers to Perl 6 today,  masak++ took some time to give them all an excellent tour of the Perl 6 universe.  Based on masak’s introduction, several of today’s attendees were able to quickly start contributing some very useful additions to Perl 6 and Rakudo.

* Marcus Ramberg vastly improved the “-h” option to the Rakudo executable, listing many more of the available and useful options. Then Marcus and tadzik++ fixed up the “–doc” option as well, which extracts documentation from the program code and displays it in a readable form.

* masak++ stumbled across a bug involving comparisons of Pair objects with uninitialized variables; we ultimately tracked it down to an issue of comparing things against +Inf and -Inf. A couple of short patches fixed that problem.

* Geir Amdal added some methods to IO to retrieve file stat times from the operating system. We had these method in the Beijing release but they had not yet been ported to nom — it’s good to have them back.

* Salve (sjn++) and several other hackers started a project of developing a much better set of reviewed examples for newcomers to examine. I pointed out the perl6-examples repository (which hasn’t had updates in quite a long time) and suggested they work on adopting/reorganizing it. At sjn’s suggestion, moritz++ added the push hooks so that commits to perl6-examples show up on the #perl6 channel, and throughout the day we were all treated to seeing improvements to the existing examples and hearing very useful comments about what the folks were seeing and experiencing there.

* sjn++ also asked about how one would determine the Rakudo version number from within a program; while that information has been somewhat available via $*PERL<version>; it wasn’t really in a useful form. So, late this evening I reworked the implementation of $*PERL somewhat so that it’s possible to determine the compiler, compiler version, compiler release number, and other information. moritz++ also at one point needed a way to determine the version of nqp being used to build Rakudo; I didn’t add it yet but will squeeze that in tomorrow. I’m not entirely happy with the way $*PERL is set up now; hopefully we can get some design and specification clarifications for it soon. At any rate, compiler version information is now available to programs to examine.

* On a related note, while reviewing version number information in Synopsis 2 I noticed that there’s a Version class we don’t yet implement — it doesn’t seem too hard to add so I may prototype one tomorrow.

* jnthn++ and I were able to spend some much needed time plotting out the next moves for the AST implementation, currently called QAST. QAST is part of the nqp implementation, and is the successor to PAST (part of the Parrot repository). Some of the refactors we’ll be able to make in QAST look like they will enable huge improvements in speed, readbility, and writability of compilers in NQP. (See jnthn++’s blog post for more details on QAST.)

There’s of course much more that happened, including many bug fixes and improvements, but those are some of the bigger items. I’m hoping to find some time tomorrow to chase down some largish bugs in Rakudo’s regular expression engine, to ease the pain further for others. I think we may also have a discussion about Rakudo’s List implementation and its features and next steps.

My thanks again to Salve, Jan, and Karl for organizing this hackathon – it has really enabled us to resolve some long standing issues and make good plans for the next phases of development.


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FLL: Matching LEGO wheels

This last fall my wife and I sponsored and coached a FIRST LEGO League robotics team that competed in the North Texas FLL Regional Tournament. We all had a great time and learned a lot. In the process we also discovered many helpful tips and ideas, but some of them weren’t available on the web or were difficult to locate. I’ve decided to collect and publish some of the ideas here so that (1) we’ll remember them for next year and (2) others can possibly benefit.

One of the things we discovered is the importance of matching wheels when building the robot. Intuitively one expects all LEGO wheels of the same type to be exactly the same size (i.e., have the same circumference). We found the reality to be quite different; two otherwise identical-looking wheels can in fact have substantially different circumferences in use. If the wheel circumferences are different, it’s harder to get the robot to reliably go straight.
Continue reading

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Some thoughts on YAPC::EU 2011

YAPC::EU 2011 in Riga has just about finished, and it has been great seeing long-time friends again and making new ones. I’ve heard many people remark that we really wish there could be more weeks like these.

There are two items that stand out in my mind about this year’s conference:

1. Andrew Shitov and his crew are absolutely amazing at organizing and running a conference. This was the most flawlessly executed conference or event I think I’ve ever been to. Not only that, but Andrew and the other organizers made it look effortless, which to me is a mark of true greatness. I’m certain that in fact there was a lot of planning and effort behind it, but the entire team just looked relaxed and at ease throughout the event. I’d definitely encourage folks to attend any event that Andrew and this group organizes.

2. Riga is a stunningly beautiful place. I definitely want to return here again some day, and I’m grateful that the organizers chose this location.


Posted in perl6, rakudo | 2 Comments

New regex engine for nqp and nom, now passing 7K spectests

Nom and nqp now have a new regular expression engine (currently known as “QRegex”) that I’ve implemented over the past week.

As progress continued on the new “nom” branch of Rakudo since my last posting, it was becoming increasingly evident that regular expression support would end up being the next major blocker. I think we were all expecting that nom would initially use the same regular expression engine that nqp (and nqp-rx) have traditionally used. However, as I starting working on this, it began to look as though the amount of effort and frustration involved would end up being almost as large as what would be needed to make a cleaner implementation up front, and would leave a quite messy result.

So, last week I started on designing and implementing a new engine. Today I’m happy to report that nom is now using the new QRegex engine for its pattern matching, and that making a new engine was undoubtedly a far better choice than trying to patch in the old one in an ugly manner.

So far only nom’s runtime is using the new regex engine; the nqp and rakudo parsers are still using the older (slow) one, so I don’t have a good estimate of the speed improvement yet. The new engine still needs protoregexes and a couple of other features before it can be used in the compilers, and I hope to complete that work in the next couple of days. Then we’ll have a good idea about the relative speed of the new engine.

I’m expecting QRegex to be substantially faster than the old one, for a variety of reasons. First, it should make far fewer method calls than the old version, and method calls in Parrot can definitely be slow. As an example I did some profiling of the old engine a couple of weeks ago, and the “!mark_fail” method accounted for something like 60% or more of the overall method calls needed to perform the parse.

Qregex does its backtracking and other core operations more directly, without any method calls for backtracking. So I expect that this one change will reduce the number of method calls involved in parsing by almost a factor of 3. Other common operations have also eliminated the method call overhead of the previous engine.

The new engine also uses a fixed-width encoding format internally, which means that we no longer pay a performance penalty for matching on unicode utf-8 strings. This will also enable us to eventually use the engine to do matching on bytes and graphemes as well as codepoints.

I also found quite a few places where I could drastically reduce the number of GCables being created. In some cases the old engine would end up creating multiple GCables for static constants, the new engine avoids this. A couple of new opcodes will enable QRegex to do substring comparisons without having to create new STRING gcables, which should also be a dramatic improvement.

I’ve already prototyped some code (not yet committed) that will integrate a parallel-NFA and longest-token-matching (LTM) into QRegex, so we’ll see even more speed improvement.

And did I mention the new engine is implemented in NQP instead of PIR? (Although it definitely has a lot of PIR influence in the code generation, simply by virtue of what it currently has to do to generate running code.)

Ultimately I’m expecting the improvements already put into QRegex to make it at least two to three times faster than its predecessor, and once the NFA an LTM improvements are in it ought to be even faster than that. And I’ve already noted new places ripe for optimizations… but I’m going to wait for some new profiles before doing too much there.

Another key feature of the new engine is that the core component is now a NQP role instead of a class. This means that it’s fairly trivial for any HLL to make use of the engine and have it produce match objects that are “native” to the HLL’s type system, instead of having to be wrapped. The wrapping of match objects in the old version of Rakudo was always a source of bugs and problems, that we can now avoid. Credit goes to Jonathan Worthington for 6model, which enables QRegex to do this, and indeed the ability to implement the engine using roles was what ultimately convinced me to go this route.

While I’ve been working on regexes, Moritz Lenz, Will Coleda, Tadeusz Sośnierz, Solomon Foster, and others have continued to add features to enable nom to pass more of the spectest suite. As of this writing nom is at 244 test files and 7,047 tests… and that’s before we re-enable those tests that needed regex support. The addition of regexes to nom should unblock even more tests and features.

Some of the features added to nom since my previous post on July 2:
* Regexes
* Smart matching of lists, and other list/hash methods and functions
* Fixes to BEGIN handling and lexicals
* Implementation of nextsame, callsame, nextwith, callwith
* More introspection features
* Methods for object creation (.new, .bless, .BUILD, etc.)
* ‘is rw’ and return value type checking traits on routines
* Auto-generation of proto subs
* Junctions
* Backtraces

We’ve also done some detailed planning for releases that will transition Rakudo and Rakudo Star from the old compiler to the new one; I’ll be writing those plans up in another post in the next day or two.


Posted in nqp, perl6, rakudo | 4 Comments

More nom features and spectests, still 5x faster than master

Progress continues on the nom branch of Rakudo. As of this writing we’re up to 89 spectest files and over 1000 passing spectests, which is a good improvement from just five days ago.

We continue to see that nom performs much better than the previous version of Rakudo. Moritz Lenz added enough features to be able to run the mandelbrot fractal generator under nom, so we can compare speeds there. Under master a 201×201 set took 16 minutes 14 seconds to run, in nom it “naively” took 4.5 minutes, and with some further optimizations Moritz has it running in 3 minutes, for a factor five improvement over the existing master branch. And there are still many more compiler-level optimizations that remain to be worked on.

In the past couple of days I added the metaoperators back into nom. Furthermore, the new implementation is far more correct — metaoperators such as &infix:<X> and &infix:<Z> can now handle multiple list arguments instead of just two as in master. We still haven’t added back the hyperoperators; I plan to do that in the next couple of days.

Jonathan has been attending the Beijing Perl Workshop this week; his presentation slides are now available at http://jnthn.net/articles.shtml. Videos may be available soon. Even with his travels, Jonathan has continued to implement some of the needed lexical and role support in nom, so that we’re generally unblocked in making needed progress in the branch.

Carl Masak wrote a post introducing the Perl 6 type system; after reading an early draft of his post we discovered that several of the builtin types (Code, Attribute, Signature, Parameter) have been mistakenly implemented as subclasses of Cool. We’ve now fixed this in nom; we may or may not fix it in master.

Indeed, we’re already starting to phase out the master branch altogether. Yesterday I made a commit to master that effectively freezes it to always test against a specific revision of the spectests. This means we’re free to fudge and adapt the tests to the needs of the nom branch without concern for what it might do to testing in the master branch.

Speaking of tests, Moritz gave me some useful shortcut links for viewing different reports in our RT ticket queue. I’ve now set up a page on rakudo.org at http://rakudo.org/tickets/ where we can collect these report links and describe how the ticket queue works. One of the more useful links is http://rakudo.org/rt/testneeded ; this link shows a list of tickets that can be closed as soon as someone is able to confirm (or add) an appropriate test in the spectests. Writing tests is fairly easy, if you’re interested in helping with Perl 6 development, this can be a good place to start.

Here’s a summary list of features added to the nom branch since my last posting (five days ago):

* Complex numbers and numeric operator fixes
* Complex numbers have two native nums instead of Num objects
* Rat literals
* List.pop, List.reverse
* Initial LoL (list of lists) implementation
* map and grep
* Many string methods and functions
* metaoperators: Rop, Zop, Xop, !op, op=, [op], [\op]
* infix:<===>, infix:<eqv>
* Hash and Array hold Mu values, scalars default to Mu constraint
* Fixes to Configure.pl and –gen-parrot=branch
* Proper handling of $_, $!, and $/
* Improved exception handling and reporting
* Hash and List slices, including autotrim on infinite indices

In the next few days I plan to have regexes working in nom, finish off the metaoperators, and improve string-to-number conversions (including radix conversions).

For people looking to learn some Perl 6, to help others with learning Perl 6, or to do a bit of both, Bruce Gray has started “Flutter” — a suite of “micro-demonstration screens” for Perl 6. Essentially each screen introduces or demonstrates a Perl 6 feature or concept. Flutter is still in the embryonic stage, so it could use both content and implementation improvements and I’m sure that patches and pull requests will be extremely welcome.

We can still use help with triaging spectests and other tasks, if you’re interested in hacking on code or otherwise helping out, email us or find us on IRC freenode/#perl6. We can also use help with adding useful links and developer information to rakudo.org, if you’re inclined to do some of that.

Posted in perl6, rakudo | 1 Comment

Lots of Rakudo-nom progress, starts to run spectests

The nom branch of Rakudo continues to develop at a blistering pace. Yesterday nom finally had a working Test.pm, which meant we could start testing it against the spectest (“roast”) suite. As of this writing nom is passing 50 spectest files. By way of comparison, the master branch passes 551 spectest files, so we’re already about 9% of the way there. And I expect that number to grow — many of the spectests fail because nom is missing relatively minor features that can be easily restored. At this rate, I’m thinking it’s very possible that the next monthly release of Rakudo (July) will be based on the nom branch instead of the old master branch.

I’ve also worked further on nom’s list implementation, and it’s now faster than lists and iteration in master. In fact, for loops in the nom branch now run about 80% faster than they did in the master branch.

We continue to eliminate PIR from the code base in nom. For the core setting, we’re down to 143 instances of ‘pir::’ and 22 instances of ‘Q:PIR’. The rest have been replaced by generic ‘nqp::’ opcodes that can someday be targeted to other virtual machine backends. Currently we’ve defined about 83 nqp:: opcodes that are used in implementing the core setting. For efficiency reasons we might not ever be able to eliminate all PIR from the core setting, but we should be able to get it to be small enough that it can be walled-off into VM-specific code files.

To give an idea of how fast things are moving — here’s a summary of the features that have been added to nom in the past seven days:

* fail()
* lexically scoped returns
* for-style loops and map, 80% faster than master
* better infinite lazy list handling
* gather/take
* try statements
* package-scoped variables, subs, and methods
* whatever currying
* Test.pm
* lots of builtin operators and methods
* dynamic variables, PROCESS and GLOBAL namespaces
* IO objects, including $*IN, $*OUT, $*ERR
* literal values in signatures
* quantified method dispatch (.?method, .+method, .*method)
* basic roles, including Associative, Positional, and Callable
* basic support for natively-typed lexicals (e.g., ‘int’, ‘str’, ‘num’)
* argument interpolation
* list assignment
* new say and .gist semantics
* magical string increment and decrement
* sequence operator
* series operator
* preliminary BEGIN/CHECK/INIT/END phasers
* smart matching (~~)
* inlined assignment

So, you can see things are active. We’re also in need of testers and people who can help us triage spectests and figure out what is causing them to not run. If you’re interested in hacking on code or helping with the tests — email us or find us on IRC freenode/#perl6!

Posted in perl6, rakudo | 1 Comment

Perl 6 lists, episode 1

This past week I’ve worked on adding list support to nom, including lazy lists and infinite lists. Lists in Perl 6 have had a bit of a convoluted history; early drafts were very non-specific about how Lists should work, and early designs tended to run into problems during implementation, leading to many redesigns of the spec.

Rakudo has gone through at least five different re-implementations of lists and arrays; the latest occured in Summer 2010 in preparation for the Rakudo Star release. Lists are extremely core to all of Perl 6, so small changes tend to impact the entire codebase. Also, features such as laziness and infinite lists invalidate many assumptions we Perl programmers have about working with lists and arrays. For example, asking a list for its size (i.e., +@a) generally destroys any laziness it might have had, as it has to go and generate all of its elements. Similarly, storing a lazy list inside of an array loses laziness, since array assignment is eager in Perl 6.

(For those who are wondering: array assignment defaults to eager evaluation because otherwise you get all sorts of surprising and non-Perlish action-at-a-distance effects.)

Similarly, passing I/O objects to various list functions would end up consuming the I/O stream entirely, such that the contents were lost to the caller. But you don’t want to adopt a model where you preserve every element all of the time, because then filters such as map and grep fail to act like pipelines and become very expensive in terms of memory consumption.

So, the Perl 6 specification and implementations have been through quite a few false starts before landing on a lists API that seems to work. We now have Lists, Arrays, Parcels, Captures, LoLs, Nil, Scalars, Seqs, flattening, interpolation, sinks, “mostly eager”, “mostly lazy”, and a bunch of other things that are used behind-the-scenes to get things to “just work” for the typical Perl 6 programmer. If seeing all of these new types frightens you, then perhaps a physics analogy helps: many of the details are like quantum physics to chemists — the Perl 6 implementors have to understand the quantum physics, while Perl 6 programmers can do a lot of useful chemistry without having to be aware of the gory details underneath.

Rakudo (master) contains the “first-draft” implementation of the latest lists API, developed last summer. Its emphasis was more on “get something working for Rakudo Star” than “make something elegant and efficient”. The key insight that enabled us to finally get something working is that iterators have to act immutable. More on this in a later post.

My original plan was to go back and revisit lists in Rakudo master, but with the “nom” branch making as much progress as it has (over 500 commits in the last 30 days!), I’ve decided to work on it there first. Nom’s new object and a ton of other internal improvements make the implementation a lot easier. In fact, unlike the previous implementation of lists, this new one is being written almost entirely in Perl 6. For efficiency reasons we may later convert parts of the newimplementation back to PIR, but we’ll do that only after we have a working P6 implementation first and we can benchmark it to see where the bottlenecks are.

Thus far the new implementation is working out extremely well. Because it’s in Perl 6, and because we now have far better object and container models than we previously had, it’s a much cleaner and more elegant implementation than before. So far it’s still slower than Rakudo master’s lists (which are already horribly slow), but it is also much easier to inspect and optimize than it was previously. For example, yesterday I was able to hotpath the code for generating numeric ranges such that it’s now several orders of magnitude faster than what we have in the master branch. Jonathan was able to profile the code and found a memory leak and another 30% improvement. So, we expect great increases in performance very soon. As far as capability, nom’s lists already handle some features that Rakudo master doesn’t get right yet.

I have a pending Hague Grant to write up the documentation for lists in Perl 6, primarily Synopsis 7. (The current Synopsis 7 draft is at least two iterations out of date with respect to the current design, which confuses a lot of people.) Over the next week or so I’ll finish up the implementation in nom, then write up the results as the new Synopsis 7 and make edits to the other synopses as appropriate. I’ll mark progress here on the blog and provide some examples of the various concepts as that progresses.

If you’re just dying to see what we have now, the source code for Lists and the other builtin types is available from the nom repository on github, in https://github.com/rakudo/rakudo/tree/nom/src/core .


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