2015.13: The first weekly of 2015 that won’t be mistaken for a monthly!

Hi! This week marks the first week this year where the week number (as per ISO something or other) that’s bigger than 12. A few weeks ago, I got up in the middle of the night and read on the IRC that someone was surprised about the number of the weekly i had just released before going to bed. I was so surprised (and still tired) that i immediately “fixed” the number to what the current month was. Silly me!

Anyway, here’s what’s new in the land of the perls and moars:

REPL improvements

hoelzro has been working on removing linenoise – the readline replacement we’ve been using in MoarVM that’s been a bit troublesome with regards to windows support and multi-byte characters – from MoarVM core and re-introducing it as a Perl 6 module, this time even with tab completion. In addition to that, psch has been poking at making the REPL understand when a statement has only been partially entered and when it should ask for more text to finish the statement. This will make using the REPL so much more comfortable once it’s landed!

Properness improvements

TimToady has spent some time deep in the grammar and a few operators/metaoperators here and there to make parsing more robust and correct, give better errors (or get us back to previously good error messages in regressed cases) and also made the reduction meta-operator, when applied to a list infix metaoperator like Z or X able to work properly with lists of lists, even when they are specified indirectly.

jnthn just fixed a bunch of problems with \( … ) syntax for Captures. It now accepts ; and differentiates properly between Pair objects and named parameters and also accepts flattening into the Capture with the | prefix operator.

jnthn also advanced the state of native arrays and their serialization (which mostly causes pre-compiled modules to work better) on both MoarVM and JVM. Serialization of parameterized types is also partially in now, but interning those types isn’t implemented yet.

Staying on the MoarVM side of things, rudi_s appeared on the IRC channel and dropped off a bunch of patches to make our code nicer: unused functions and variables were thrown out, functions that don’t return or where the result ends up unused were properly marked, format strings were fixed. I don’t know what rudi’s involvement will end up being, but I hope when the codebase feels more familiar to them, they’ll make some deeper changes 🙂

Performance improvements

While working on making “use nqp” a mandatory declaration for using nqp:: ops in modules, moritz found out that “nqp::time_n” is a very popular op across our ecosystem. Why is that, you ask? Because “now”, which gives you a posix timestamp with fractions-of-seconds accuracy, is terribly slow. Actually, I should say “was” rather than “is”. jnthn found out that a big chunk of the time spent in “now” comes from the coercer that turns real values (Num) into rational values (Rat). That thing is now about 6.5x faster than it used to be.

jnthn also had a close look at how spesh behaves during startup and tuned the specializer and on-stack-replacement thresholds in MoarVM to reduce overhead during startup. This impacts both memory usage and time usage.

The Ecosystem

In the ecosystem there’s now the beginnings of a Git::PurePerl port from p5 to p6, which can already clone and checkout repositories, albeit very slowly. During the week two other modules showed up, namely Linux::Fuser and Browser::Open.

Another interesting thing to point out is that thanks to a bit of work by retupmoca GTK::Simple will now download DLL files from gtk-dlls.p6c.org if they can’t be found on a windows system. This makes deploying GTK-using Perl 6 programs to windows systems much simpler. I already asked retupmoca to apply the same treatment to a few more modules.

I personally spent a bit of time playing around with HTTP::Server::Async and i’ve learned a thing or two about javascript, HTML5 technologies (in particular EventSource, which is kinda cool) and how to glue it together with Perl 6. A few things have come up that ought to be changed in HTTP::Server::Async, but tony-o (HTTP::Server::Async’s author) is already on the case.

“eleven” lands for panda!

FROGGS has merged a panda branch called “eleven”, which makes use of the CompUnitRepo functionality of rakudo. The effect is that installed distributions will not be stored as files on disk, but go into a database like thing. This is done to be able to install (and locate) several same-named versions of a distributions, or distributions made by different authors. These can now coexist, though as a consequence every distribution must have a “provides” section [^1] in its META.info.
Such a “provides” section (or an entire META.info) can be generated by running “panda gen-meta”. Modules without a proper “provides” have a panda icon with a strike-through “S11” flag next to them on the modules list, so if you want to dip your toe into contributing to Perl 6, here’s a very simple way to do so… 🙂
The CompUnitRepo database is not just there to allow looking up namespaces by distribution version or author, it also copes with the issue that arises when two distributions try to provide a binary/script with the same name. The CompUnitRepo will install wrapper scripts instead, which take –auth, –name and –ver options to select a specific binary or script to execute. If the search result is ambiguous a list of candidates is displayed to allow to refine the search criteria.
Next on FROGGS’s TODO is to implement %?RESOURCE [^2] and also to look into any fallout that happened because of his latest work.

[^1] http://design.perl6.org/S22.html#provides
[^2] http://design.perl6.org/S22.html#resource

And just like that, another week has already come and gone. This week, I’ll actually have a look at finding some interesting snippets for you to post on a different day. I’m thinking Thursday would be a good day to try. Thanks for the warm words, everyone 🙂

See you on Thursday, or at least on Monday 🙂

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