How to Count (Parrot Style)

Syndicated 2009-07-03 09:11:54 from pudge

Perl 6 Design Minutes for 20 May 2009

Syndicated 2009-07-02 23:03:51 from pudge

Perl 6 Design Minutes for 20 May 2009

The Perl 6 design team met by phone on 20 May 2009. Larry, Allison, Patrick, Jerry, Nicholas, and chromatic attended.

Larry:

• trying to delegate some of my spec writing
• if someone has something that needs to change and that person understands the design principles, someone can go ahead
• Moritz respecced each to make it a conjectural junction
• other people are working on the NFG specification
• I haven't seen any changes committed on that yet
• thinking about how importation works
• particularly with inlined modules
• expect that there will be an import declarator implied by use but usable explicitly
• if you say import with an inline module or role declaration, it'll perform the export
• which won't happen by default
• thinking about how that declaration works at the moment
• instead of trait_auxiliary and trait_verb, which fill the same syntactic category, we have trait_mod
• they all occur in the same spot
• you're always looking for them both simultaneously
• the hander routines are now all upperclass autocalled, like other handlers
• IS or TRAIT_IS or APPLY_IS, or some such
• still thinking about namespaces for typeless traits not based on classes
• perhaps rw or readonly traits aren't types
• they need to be in a namespace somewhere
• maybe just a syntactic category
• added the use of ampersand variables on method calls to STD,<nobr> <wbr></nobr>.&foo
• you can already say $.foo, call a code reference as if it were a method
• & is also a code reference; ought to be allowed there too
• Jonathan was playing with ampersand attributes,<nobr> <wbr></nobr>.&!foo
• the rudimentary POD parser now complains if you don't have a matching =end for your =begin, except in the case of =begin END
• if you put a default onto a named parameter, parser assumed it to be a positional parameter
• gave a bogus error message
• I fixed that
• another interesting grammar tweak
• defining an infix:<< >> and then a signature
• if you leave a space out between the name and the signature parentheses, it would misparse
• French angles ambiguously hyper parentheses there
• I didn't want to require the space there
• it's nice that you can write the declaration as if it a were call with the parens
• if you're going to hyperoperate on parentheses, you have to use the dot form
• >>( is now specifically not a hyperoperator within interpolation
• >>.( is
• that seems to be pretty DWIMmy
• everything else is cage cleaning and hanging out

Patrick:

• did not write any posts
• will fix that first
• mostly worked with others to make these happen
• Tene and I ported Rakudo to run in its own HLL namespace instead of Parrot's
• caused a 40-50% slowdown in execution time
• we know the cause and have a fix before tomorrow's Rakudo release
• I'll compare Rakudo's speed to before the switch
• want to credit chromatic for any performance optimizations

c:

• I have a 6.5% improvement for all function calls

Patrick:

• we have better error reporting now
• can point to the point in your code with the error, rather than some point in generated PIR code
• added the ability to define custom operators in Rakudo
• infix, prefix, postfix
• in select cases also circumfix
• we can move even more parts of the builtins to Perl 6 as a Setting
• exposed a few other places we need cleanup
• Jonathan is working on those
• added a variable to PCT which gives the compiler the names of the files it's compiling
• improved error reporting there
• added an inline PIR construct to NQP to match Rakudo's
• added the qx// quoting term
• can now run shell commands and capture the output into a variable
• answering questions online and taking care of other little things
• preparing for tomorrow's release
• though it may occur very late tonight

Allison:

• mainly release prep this week
• lots of ticket review and patch application
• submitted an article to Linux Magazine, "Why Parrot is Important"
• more high-level than a tutorial
• continuing to work on the book
• a good week for high-level design discussions
• seems like that happens when I have more time to be on IRC

Nicholas:

• an update on smart-match
• Paul Fenwick gave the position of a Perl trainer
• the design decision of not being able to overload the left side of the smart match bothered him
• there's more discussion there

c:

• optimizing Parrot and Rakudo
• finding bottlenecks
• fixing many of them
• editing the Parrot book
• doing a little more design work on nanoparrot

Nicholas:

• how far off are you from letting other people release Rakudo?

Patrick:

• the instructions are in the repository
• they're straightforward
• I could turn it over to Jonathan or Jerry or any number of people with ease
• they could just do it
• it's basically a Makefile target
• you do some prep work, run the target, then upload the tarball to the right places
• I stole liberally from how Parrot does things
• I can hand it off any time I get tired of making them

Nicholas:

• so the bus number is low

Jerry:

• any plans to turn it over soon?

Patrick:

• if other folks think it's important, I can do that
• I could pick someone at YAPC::NA to do it
• the release day is the Hackathon day there
• we could just walk a few people through it that day
• even if they don't upload the tarball and push the tag
• we'll target that for the June release, even if no one else releases an official release

Jerry:

• I've been trying to get the Parrot release bus number above 10
• we're close, which is a great place to be

Patrick:

• that was evident, as yesterday's release manager couldn't make it, and Mark Glines picked it up

Jerry:

• and it was his first release

Syndicated 2009-06-18 02:08:58 from pudge

Perl 6 Design Minutes for 13 May 2009

The Perl 6 design team met by phone on 13 May 2009. Larry, Allison, Patrick, Jerry, Will, Nicholas, and chromatic attended.

Larry:

• continuing to think about how braided languages work
• implementing the notion in the STD parser
• the notion of how you switch between these languages
• now called slangs
• thinking about how macros work in embedded lexical scopes
• if you define a role which contains a trait auxiliary definition
• label it is export
• how does it export?
• to which lexical scope?
• when you do the role or what?
• no defined way of exporting to outer
• that's a problem in some tests
• with augment slang, we have a way of embedding grammar modifications inline
• when do ordinary macros embedded in subscopes desugar to that sort of thing?
• %*LANG now holds the whole language braid
• the $*PARSER variable is just the MAIN element of that
• I backed off some of the errors in the STD parser to just warnings
• don't really handle module and role long names yet
• you get bogus "can't augment" warnings now
• it thinks something isn't there that should be there and vice versa
• fixed a test where STD needs to parse =for; now it does
• added the slang declarator so that we could augment them
• a twigil indicates a current slang subset of the current braid
• fixed a bug to recognize the invocant marker after an unspace
• that was a longest-token match problem
• the message I added about a missing block gobbled by a function is now two separate messages
• one talks about the function which needs parens
• the other talks about the missing block
• they point to two different areas as a matter of clarity
• I'm really enjoying adding clever error messages

Patrick:

• Rakudo now passes 11,200+ tests
• up by 70 tests since yesterday
• a couple of hundred in the past week
• mostly doing little bug fixes and refactors
• typically, I'll start to add a feature and find some code which doesn't look right
• then I add the feature
• slurpy arrays and hashes weren't added properly to subs
• always added automatically regardless of the type of Block
• I cleaned that up
• also cleaned up lots of parameter handling in the code
• that made actions.pm 100 lines shorter, and I removed three duplicate subroutines

c:

• that also speeds up startup

Patrick:

• every time we do that it helps
• found a bug dealing with Unicode characters in grammars
• prevented us from properly parsing French quotes as an angle delimiter
• working on adding operator parsing to Rakudo today
• define your own custom operators
• refer to them using canonical names
• expect to have that done today
• they won't be lexically scoped
• I'll work on fixing that, when we get more to lexical scopes and language braids
• continuing to consider protoregexes and LTM in PGE
• probably will implement contextual variables in NQP and Rakudo

Allison:

• we'll have packages in Ubuntu soon
• just a straight sync of the Debian packages
• no reason to make Ubuntu-specific packages, if that works
• working on editing the book
• working on the calling conventions branch
• writing a Parrot article

Jerry:

• GSoC mentors and students seem to be bonding in their bonding period
• set up parrot.org to accept donations from individuals
• there's a sidebar link under the Foundation heading
• and we received our first donation!
• thank you, Bradley Kuhn
• we'll work on placement and prominence
• think I'll give a keynote at YAPC::NA, following Larry

Larry:

• if you pay me enough, I'll run over

Patrick:

• if you don't pay him, I suspect he'll run over
• you are what stands between everybody and lunch

Will:

• added some regression tests
• made some stuff work in Perl 5.8.8, so we don't have to upgrade our dependency
• wrote a script to summarize our old branches
• convinced people to delete a bunch of old branches
• hopefully we can weed them out
• TPF's grant committee votes this week on the current crop of proposals
• one of them is for Perl 6
• if you have any comments, please post on that
• Partcl is still dead
• blocking on the ability to build a language from an installed Parrot
• we've made some progress on that
• there are still things that do not work
• most of them have tickets

Patrick:

• Rakudo's blocking on the same thing
• Tene is working on getting Rakudo to run in its own HLL
• he's blocking on the HLL load_library problem
• I'll have him post to the list and give an update on the ticket

Nicholas:

• Rafael has merged his smart-match branch back into blead
• he tried to make smart-matches match ranges
• it won't work for various reasons
• precedence is the wrong way around for one
• $foo ~~ [ 1, 2, [ 3<nobr> <wbr></nobr>.. 5 ] ] won't work either
• Perl 5 ranges aren't lazy
• smart-match can't interrogate Range objects lazily
• that's why we can't emulate everything from Perl 6
• we don't have the low-level infrastructure to do it all
• even if we had that infrastructure, there are parsing issues
• I don't see that coming in a hurry
• if someone implements lazy ranges, maybe someone can add them to smart-match
• giving the enjoyment people derive from implementing such things, I'll be surprised if anyone does that

c:

• added some optimizations
• heading toward the "not really worth doing" kind
• fixed some bugs
• including a Unicode parsing bug with named parameters and arguments in IMCC

Nicholas:

• did you write about the abolition of unary equals, Patrick?

Patrick:

• not yet
• I feel badly about that
• I need to catch up
• there are so many interesting problems to work on
• writing is not as interesting as working on code

Syndicated 2009-06-16 20:14:44 from pudge

Pelr 6 Design Minutes for 06 June 2009

The Perl 6 design team met by phone on 06 May 2009. Larry, Allison, Patrick, Nicholas, and chromatic attended.

Larry:

• refactored my phone
• refactored various functions
• comb now defaults to matching single characters
• a words method now does what comb used to do
• did some work on pick
• looked at most of the functions in containers to see whether they out to return a List or a Capture which returns an Item
• depends on whether the function would ever be used to pull a single thing out
• whether people expected it to do the right thing as an Item
• pick is one of those functions
• worked on the semantics of has
• the initializer semantics; the syntax hasn't changed
• worked on the relationship between multiple has if you have multiple attributes
• straightened out a mismatch between prefix parsing specification and implementation
• turned the term "protoobject" into "type object"
• thinking about the notion of braided languages
• Perl isn't a single language
• also a regexp language, a quoting language, a quasi-quoting language
• they hand off to each other
• they have to keep track of each other; I call that a "braid"
• how you override one language in another
• how do you handle regexp language changes from regular Perl, when you're not in the regexp language at the time?
• thinking about how to get the derivations to work correctly
• when you parse a regexp or a quote
• now instead of starting at a language like q, it starts at the current q-ish language in your braid
• in support of that, I implemented temporization of context variables in gimme5
• used to temporize current braids to a lexical scope
• added a block after try in parsing
• it uses that rather than parsing the block as the first argument of a list operator
• likewise the other statement prefix operators
• added the auxiliary hides trait
• the \c notation for characters allows any radix of integer inside the list
• the \c, \o, and \x notations all parse consistently now
• enums are parsed more correctly
• they don't give bogus duplicate warnings
• if you declare a lexical symbol with<nobr> <wbr></nobr>:: in it, assumes you're referring to a subpackage of the current lexical scope
• means something different from a symbol intended to scan outward
• along with the notion of braided languages and derivability, derived languages can add more parser variables ($?foo) with a virtual function for lookup
• avoids clobbering the core definitions
• worked on role parameters
• they're now in the role's pad, like normal signature parameters
• started playing with the YOU_ARE_HERE stub used to define the effective insertion location of your code into a Setting
• determining which lexical pad to dump as the Setting's context for use by other compilation units
• did a lot of work on error messsages
• some of my ||s suppressed panic messages
• more useful error message on the null pattern (//)
• gives a better message if you slurp your control block in the preceding expression

Patrick:

• had a lot of discussions online
• not as much coding as I like
• seem to be answering questions for others
• quite a bit of work on Rakudo internals refactoring
• that'll make it easier to switch it over to be its own HLL in Parrot
• moved things around
• made a single constant definition we can change when we move it over to its own HLL
• also moved all of the Parrot HLL mangling into its own source code files
• easy for us to manage there
• fixed some bugs
• talked with Jonathan about refactoring the P6object implementation
• used in Rakudo and PCT for Perl 6 object-like behaviors
• he's working on that refactoring now
• found and fixed a couple of bugs handling implicit slurpy positionals
• made Rakudo's standard IO handles default to UTF-8 encoding
• gives people behavior more like they expect
• working on changes to the Array and List implementation
• currently List inherits from ResizablePMCArray
• we'll change that to contain it
• that should clean up a lot of behavior
• Rakudo passed the 11,000 spectest mark as of two days ago

Allison:

• spent some time on ticket, milestone, and roadmap maintenance
• helping other people start or continue their tasks
• launched the install PDD out of draft
• it doesn't address every question, but I cleaned out all of the inaccuracies
• fits our current plan
• probably needs more expansion when we figure out the source of some of our problems building Rakudo and Partcl
• the general problem is that we've built all of our languages from the build tree, never and installed Parrot

c:

• I've been explaning Perl 6 roles on my new weblog
• lots of feedback
• still lots of explaining to do
• also been profiling Parrot and Rakudo startup
• Parrot's a lot faster now (cotto and bacek's work on vtable init helped immensely)
• Rakudo's getting faster, but it has a ways to go
• will keep working on that, but the progress has been decent with little investment
• discussed exception handling with Allison
• came up with a preliminary design to handle the interior runloop exit there
• just syntax to hide tricky semantics

Patrick:

• when dealing with exceptions, handlers, and returns for subroutines
• it'd be nice to force a return from a subroutine higher up in the caller chain
• akin to Perl 6's leave semantics
• trying to do that without throwing an exception....
• if we do it with exceptions requires every block to have a handler

Allison:

• invoke the return continuation several levels back?

Patrick:

• is that easily doable at this point

Allison:

• we have all of the ability for that, but no syntax for it

Patrick:

• I don't necessarily need syntax for it
• the natural approach is to find the appropriate caller
• I need to do that anyway
• then ask for its ReturnContinuation
• then invoke that with the values I want to return to its caller

c:

• makes sense to me

Patrick:

• that may exist in PIR syntax like that anyway
• if the easy invoke doesn't work, use some combination of set_returns

Allison:

• not sure if we have in PIR right now the way to ask the caller for its return continuation
• you can do it from C
• we can add something which does that

Patrick:

• if I ask for a Sub's current context
• I could write a method on a sub to do that
• it'll be easier and nicer when our contexts are PMCs
• as an intermediate case, that would be it
• related to that, this might be there too
• is there a way for a Sub to register behavior to execute just before it exits

Allison:

• are those like the LEAVE hooks in Perl 6?
• we have a place to store them now
• we don't right now have a way of flagging a particular handler to execute at block scope exit
• would it make sense to call that an event?

Patrick:

• it might
• before saying what we do and don't have
• one piece of this is that there's still a push_action opcode

Allison:

• it never worked
• we're removing it
• the global stack never synchronized with continuations
• it dummied up to work, but it doesn't have the automatic stack cleanup behavior

Patrick:

• the other possibility is the presence of ONEXIT or LEAVE hooks on Subs in Parrot

Allison:

• do you want all Subs to have that
• or at runtime would you want to attach a handler to that sub?

Patrick:

• it might be nice to have that at compile time
• I suspect it'll end up being an attached block

Allison:

• can we tie that cleanly with other execution pieces?
• NEXT and LAST etc

Patrick:

• the biggest difference with LEAVE is that it's not exception-based
• Larry thinks of it as natural to a block
• PCT models the rest as exceptional

Allison:

• it sounds like a handler to store in the local handler list
• mark it so that it's clearly not an exception
• we have handler flags -- exception, event, etc
• we add to the execution code for Subs
• as it returns or ends, it checks to see if there was a handler
• invokes it if so

Patrick:

• sounds good to me
• it's come up if you're thinking about these issues anyway

Nicholas:

• how useful is MAD that's in Perl 5 blead still?

Larry:

• I don't know
• it may turn out to be very important
• depends on how possible it is to write a decent Perl 5 parser in Perl 6
• where decent is a very peculiar definition meaning "indecent"
• this is unknown
• for interleaving Perl 5 and Perl 6 on various VMs, some VMs will use a Perl 5 compiler written in Perl 6
• that may not be a solution as nice as using the real Perl 5 parser which knows its own idiosyncracies

c:

• sometimes it does

Larry:

• that's the point
• I'd hate to have to have to hack it up again
• that was a lot of work

Nicholas:

• it seems to suffer slow bitrot
• no one seems to try to keep it up to date
• when people change the parser, they don't change it
• the question is if people still use it

Larry:

• the vision is still to have a Perl 5 to Perl 6 translator
• that's been on hold until we have a viable target to translate to
• the demand for that will re-arise at some point
• if it bitrots, it bitrots
• that doesn't bother me as much as if people felt like ripping it out
• the way to unbitrot it was roundtripping the test suite and fixing any problems
• we'd just go back to doing that again until everything was reannotated the way it needs to be
• the standard for when you know you're storing enough information is being able to reproduce it

c:

• is there a test target to handle that?

Larry:

• I used special scripts to do that
• didn't expect other people to maintain that
• it's MAD for a reason
• nobody's tried to write a Perl 5 parser in Perl 6 yet
• it's theoretically possible

Patrick:

• depending how much fidelity you need for the actual Perl 5, you can get a pretty good way

Larry:

• considering how much effort has gone into PPI, you can get a PPI-like result
• that only takes you so far though

Patrick:

• maybe a GSoC project next year would be for someone to start hacking something together with PPI
• it'd be a worthwhile project

Larry:

• we already have a Perl 5 to Perl 6 translator based on the state of MAD

Syndicated 2009-06-16 01:38:38 from pudge