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chromatic (983)

chromatic
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http://wgz.org/chromatic/

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Journal of chromatic (983)

Wednesday April 28, 2010
05:20 PM

Perl 6 Design Minutes for 21 April 2010

The Perl 6 design team met by phone on 21 April 2010. Larry, Allison, Patrick, Will, Jerry, and chromatic attended.

Larry:

  • been under the weather, so didn't get much done other than keeping up with questions
  • S05 now allows negative quantifier ranges on reversible patterns
  • S02 now defines the term now to return the current instant
  • like rand and self, it does not parse as a function, since it never takes arguments
  • we now specify what kinds of math are allowed on instants and durations
  • improved error message on attempt to use old-school backreferences in regexes
  • STD now implements the now term and several other time-related names
  • we now allow enum names to be "constant variables" so that a class enum can declare an accessor
  • thinking alot about a better unification of the semantics of protos
  • this may also solve the current ambiguity in the meaning of postfix parens
  • in any case, this is for post Rakudo *

Allison:

  • mainly worked on packaging for Debian and Ubuntu before the release
  • closed TT #389, no methods in namespaces
  • collecting thoughts on what we need next from the GC
  • we've done a lot of small cleanups
  • now we need to solve some persistent problems
  • might need to make some fundamental changes, like reducing copying
  • coming up on my final week of classes, so lots of work there coming up

Will:

  • updated a spectest
  • minor ticket wrangling in Rakudo's RT queue

Jerry:

  • GSoC will make its acceptance announcements soon
  • expect TPF will get 10 slots

Patrick:

  • reviewing Rakudo's current state
  • made a couple of minor NQP patches
  • reviewing patches, especially from Moritz and Bruce Keeler
  • should check them in, probably with some refactorings
  • hope to work on the List implementation, especially laziness and context

c:

  • fixed as much of line numbering as I found broken
  • working on branch merges
  • still looking at optimizations
  • will focus most energy this month on the sweep-free GC
  • hope to encourage other people to work on identified optimizations
  • will review Solomon Foster's Mandlebrot example, especially with regard to performance
Tuesday April 20, 2010
11:09 PM

Perl 6 Design Minutes for 14 April 2010

The Perl 6 design team met by phone on 14 April 2010. Larry, Allison, Patrick, Will, and chromatic attended.

Larry:

  • on p6l, did a bit of bikeshed paint removal with regard to hyphens vs underscores
  • S02 now explicitly disallows both whitespace and unspace in top level of an interpolation
  • per spec change, when STD is parsing an interpolation inside quotes and looking for a possible postfix, we now presume that a backslash belongs to the quotes and is not an unspace
  • in the src/perl6 directory, renamed all Perl 6 .pm files to .pm6 to avoid confusion
  • this was necessary because the implementation of STD translates Perl 6 back to the corresponding Perl 5
  • the ambiguity was causing problems with tools such as NYTProf
  • Cursor.pmc now prefers .pm6 over .pm in any particular directory when searching for Perl 6 code
  • as usual lately, most of my hacking work was in improving the human interface of the parser
  • STD now distinguishes two final messages: "Parse failed" vs "Check failed"
  • STD now warns on attempts to smartmatch with True or False
  • STD now distinguishes continuable-but-fatal "sorry" messages from immediately fatal "panic" messages
  • sorry messages will eventually fail at check time
  • changed many of STD's semantic errors to use sorry messages when the parse state is not affected
  • modified moritz++'s conflict marker patch to be more like the Clang compiler's behavior
  • conflict markers now emit a "sorry" message and continues parsing one side of the conflict
  • also fixed a buglet that prevented it from processing the conflict marker if first thing in the file
  • while fixing the vws (vertical white space) rule for that, also changed it so that extra lines are now eaten with \V*\v for consistency
  • it had be using \N*\v
  • gimme5 now supports pointing to both ends of missing goal message
  • STD's "Couldn't find final ..." messages now use that capability to point to both ends of the error
  • standard quotes now also use the ~ compositor to set the goal and get that behavior
  • STD will now dwim <<op>> ("Texas hypers") better even if op contains angles
  • suppressed confusing backtracking on ~<< that produced a misleading quotewords error
  • some other patches
  • CORE.setting now recognizes the 'note' function
  • gimme5 now translates note to print STDERR
  • cleaned up some unneeded locmesses
  • Actions.pm now handles prefix metaops without spewing spurious yaml dumps

Allison:

  • worked on TT #389
  • the actual fix was about two lines
  • spent a lot of time fixing tests around it
  • didn't like the original two-line fix
  • fixed it in IMCC by passing along the :nsentry flag
  • NQP-rx still depends on that feature
  • I understood from Patrick that NQP-rx doesn't need that feature
  • don't want to launch that before the 2.3 release
  • worked on a lot of smaller issues
  • worked on the Parrot Developer Virtual Summit
  • will talk about some process changes more, as there are details to work out
  • will work on GC as the next priority
  • useful for Rakudo in general and Parrot concurrency

Patrick:

  • catching up on mail and tickets
  • should get back to coding in the next couple of days

c:

  • worked on the immutable strings branch
  • need a couple of changes in the Rakudo binder
  • now it's time to convince everyone else it's a worthwhile design change
  • going to work on bugfixes
  • will try to land the constant string cache
  • otherwise, added some optimizations

Will:

  • worked on Partcl
  • fixed a Parrot bug that broke Rakudo
  • does Rakudo need TT #389 in 2.3?
Friday April 09, 2010
05:07 PM

Perl 6 Design Minutes for 07 April 2010

The Perl 6 design team met by phone on 07 April 2010. Larry, Allison, Patrick, Jerry, Will, and chromatic attended.

Larry:

  • clarified that object identity from WHICH may not be a mundane value type
  • instead object id's are of type ObjAt to avoid type name collisions.
  • rewrote misleading description of "thunk"
  • made some clarifications of the desired semantics of buffers
  • Buf is primarily a role for dealing compact, unsigned integer arrays in a stringy way
  • but a Buf may be instantiated with other numeric types as well.
  • removed bogus mentions of Buf8, Buf16, Buf32; only the native buf types are sized that way
  • STD now actually parses the insides of tr/// and carps about malformed ranges
  • labels are now stored symbolically as constants rather than types
  • so no coercion routine is added for the name, so it doesn't collide with the function namespace
  • labels are now constants with a unique label type to prevent confusion with ordinary constants
  • module subcompilation now reports the name of the file it's compiling
  • improved various error messages regarding foreach, !!op, $!{}, EOF, and missing punctuation after blocks

Allison:

  • worked on line number reporting in HLLs
  • no ticket to go on, no good examples
  • didn't make much progress, but didn't have much time
  • sounds like Christoph and chromatic are working on it
  • might look at TT #389

c:

  • you're welcome to it!
  • let me know if you have questions; it's close

Allison:

  • no travel plans for the next couple of months
  • should have a lot more Parrot time
  • probably time to consider another big project
  • probably GC related

Patrick:

  • updated the progress graph last night
  • up to date as of yesterday
  • Rakudo's passing over 30,000 tests, which is great

Jerry:

  • we have 27 mentors signed up for GSoC
  • a dozen student proposals have come in
  • the admission period ends Friday, so I expect at least a handful more
  • looks like a good year for proposals
  • trying to keep on track of Rakudo development
  • trying to be a go-between for Rakudo and Parrot
  • seems like it's helping Rakudo as Parrot addresses issues that come up

c:

  • Vasily and I fixed the Rakudo performance regression
  • we're going to experiment with immutable strings in a branch
  • expect some notable performance improvements there
  • also worked on the plan to fix line number reporting
  • need a test harness to help identify problems and avoid regressions
  • learned my lesson last time I worked on that....

Larry:

  • I cringe every time I hear "line numbers"
  • I like what Clang does about highlighting the arguments to functions
  • it'd be nice if we can do similar

c:

  • that'd require more changes to Parrot, but it's doable

Larry:

  • I just want people to bear it in mind

Allison:

  • there's no reason we can't have richer annotations
  • our first step is making sure the information we provide them (or they ask for) is accurate
  • is it time to have another big development meeting for Parrot?
  • the release is coming up

Jerry:

  • sounds good
Sunday April 04, 2010
11:42 PM

Perl 6 Design Minutes for 31 March 2010

The Perl 6 design team met by phone on 31 March 2010. Larry, Allison, Patrick, Will, and chromatic attended.

Larry:

  • in SpecLand, made it clear that the brackets in pairs are not related to subscripts, but follow the corresponding fatarrow semantics
  • in particular, name extenders are just strings or list of strings, properly indicated by : or :() in most cases (this includes all operator names).
  • we now forbid name extension using the :{} keyless adverbial syntax
  • we don't need that because name extensions are really only supposed to use values, not closures
  • if we really, really, need to supply a closure as part of a name extension, we can put it in parens, as in :({}).
  • we can use that notation for supplying a closure as a first argument to a method without requiring a space between the colon and the curly, as in .map:{...}
  • people keep writing that and expecting it to work, so I thought it would be good to make it work
  • the colon is still require before the curlies, or it's a hash subscript
  • we now capitalize the Junction type again because I couldn't get people to stop capitalizing it
  • also, the native aspect of junctions is not their most salient difference from normal types
  • conjectured an Each type that autothreads lists like junctions, but is serial and lazy, and is used for its values in list context, not boolean context
  • in S05, did much cleanup of cursor semantics to reflect what STD and Rakudo actually do these days
  • retargeted the <&foo> regex assertion form to explicitly call a routine, just like <.foo> always calls a method
  • a bare <foo> assertion now prefers to call a lexical function if visible, or calls as a method in current grammar if not
  • this is a compile-time distinction, not a fallback at run time
  • in code hacking, continued debugging of the backtracking transactions I added last week
  • gimme5 now sets the correct xact on || alternations
  • deleted more of the transactions that are no longer needed when building match results that are no longer hypothetical
  • a LazyMap now always passes through the first result regardless of its associated commit transaction state
  • that's because the first cursor in a lazy list always represents the current match hypothesis, not a future hypothesis that needs pruning
  • STD now parses to the new specs regarding name extensions not including :{}
  • now allow colon form of method arguments to omit the space if the next char is a left curly, which is what people seem to expect anyway
  • note that this makes the closure the first argument, not the only argument
  • STD now gives more useful error messages when user says things like 'if' as a function call (if(...) {...}), or a statement control like 'given' where one isn't expected ($x = given {...})
  • STD now properly objects to unrecognized internal regex modifiers such as :has
  • improved the message on adverbs with empty angles (:foo<>) to list some better options
  • the problem arises when people think that the angles produce a null string, when in fact they produce a Nil list
  • other malformed pairs are also better diagnosed, such as :! not followed by an identifier, or pairs with duplicate arguments
  • added a new rule that traps all warnings and errors
  • STD now uses suppose in place of custom try blocks in diagnosing such things as two terms in a row, or unexpected infixes
  • also uses suppose to soften the warning about backtick-less embedded comments by not complaining if the supposed comment eats the whole line anyway
  • put in some code to de-dup identical warnings
  • STD now includes the signature's return type (after -->) in the check for redundant 'of' types
  • did various tiny speed tweaks, fossil removals
  • started playing with how to mark sink context and pure operations
  • split out Actions.pm from viv so that it can be used by other STD-based AST builders
  • this is in preparation for propagating attributes up and down the AST such as sink context and purity
  • eventually this will result in "Useless use of" messages where appropriate, not to mention the ability to do constant folding

Allison:

  • worked on the compact_pool() function
  • split it into a series of smaller functions
  • it could use more work, but it's an improvement
  • found one possible bug
  • worked on some documentation, especially for PMC attributes

Patrick:

  • reviewed some patches to add variable handling in regexes
  • they need some changes, but the overall concept is good
  • reviewed a few other messages
  • most of my time is going toward my family
  • hope to get more time to be more active in the next couple of days, but I can't promise that yet

Will:

  • talked to Jonathan about Rakudo Star priorities
  • he's very pleased with the memory fixes
  • the next thing on his list is getting good line numbers in reported errors
  • closing tickets
  • working to get rid of the last recursive Makefile
  • may wait until after the new release, when we remove a lot of deprecated things
  • practicing my NQP skills by working on Tcl again

c:

  • worked on the Rakudo memory problems
  • Vasily and I fixed the big memory use problem
  • still some performance tuning to do there
  • wrote up tasklists for two other important performance pieces
  • will work on line numbers after we get performance back
Wednesday March 31, 2010
04:20 PM

Perl 6 Design Minutes for 24 March 2010

The Perl 6 design team met by phone on 24 March 2010. Larry, Allison, Patrick, Jerry, and chromatic attended.

Larry:

  • clarified that nearly all normal operators autothread, including === and eqv
  • specced the \| parcel parameter syntax
  • documented that R metaoperator does not change associativity
  • clarified that trusts traits do not extend to child classes, and moritz++ specced it
  • in STD, we now suppress spurious errors from badinfix lookahead (and react more accurately to bogus terms)
  • now put the error location pointer before a bad infix, not after
  • we no longer assume missing block punctuation is always semi or comma, but keep them as a suggestion
  • missing punctuation message now points before any whitespace
  • awesomified error message about no unspace in regexes to explain how to quote space or #
  • pass single coeff to radcalc to make :16<.BABEFACE> easier to allow
  • gives better message on missing ** part of radix literals
  • worked around fact that :: doesn't correctly suppress relexing of multi tokens
  • scrapped the workaround and did a complete refactor of commit point transactions; no longer uses exceptions to commit
  • instead, it walks the current commit chain to the proper commit target to disable choosers that should not choose any more options
  • commit chain aliasing and forking to make a cactus stack is now managed by cursors, mostly transparently
  • weighed in on the subject of stability domains (or lack thereof) in Rakudo *

Patrick:

  • still working on personal issues, but hope to have some resolution by Saturday
  • haven't had much time to work on Rakudo, but show up on #perl6 to give advice sometimes
  • read Larry's email to the list; it was very helpful

Allison:

  • met some interesting people at SxSW doing open source education technology
  • reviewing the roadmap
  • the GC sounds like the most important thing to work on next
  • trying to catch up from having spotty network access lately

Jerry:

  • the other Rakudo developers have started weekly planning meetings
  • Jonathan has taken the lead
  • plenty of contributors are in the meeting and offered to take on new tasks
  • Rakudo Star may have a smaller scope, but it'll still come out in Q2
  • it's nice to see that the Rakudo community continues even as Patrick has an extended absence
  • still some Parrot issues affecting Rakudo
  • PaFo hopes to have its 501(c)3 application done by summer

c:

  • bugfixes
  • minor optimizations
  • helped merge the PCC refactor branch
  • working on Rakudo memory issues (long analysis follows, partly Parrot GC and partly NQP behavior)
04:17 PM

Perl 6 Design Minutes for 17 March 2010

The Perl 6 design team met by phone on 17 March 2010. Larry, Allison, and chromatic attended.

Larry:

  • documented which ops don't autoclose with *, including assignment
  • conjectured a generalization of the closure-calling context (value-only lists) that subscripts enforce
  • this generalization might allow the autoclosing of some of the current exceptions such as 1..*
  • added Z to go with X metaop; documented that X and Z desugar to higher-order methods, crosswith and zipwith
  • speculate about how to zip/cross dwimmily with non-identical ops; possibly creating a real use case for surreal precedence
  • however, for now sticking with conservative approach of requiring parens on differing list infixes
  • hacking on viv again
  • trying to get that bootstrapped, so I don't have to use gimme5
  • unbitrotted viv --p6 so it exactly reproduces STD.pm again
  • various developments with viv --p5 toward replacing gimme5
  • should make it easier to emit other parsers eventually
  • may emit Rakudo code someday
  • it's a race to see whether STD can do that before the current Rakudo parser resyncs with STD
  • anyone who wants to bootstrap on some other VM might want to use that
  • mostly tired of writing in the subset of Perl 6 that gimme5 understands
  • mostly hacking on better error messages, as always
  • catches use of non-$ hard reference
  • STD now read minds of people who forget that ".meth I" is a two-terms-in-a-row error
  • now produces good messages on attempts to use y/// or tr/a-z/A-Z/ syntax
  • now reports "previous line missing its semicolon" in the unexpected block checker
  • ambiguous use of . probably indicates p5-think, not missing method parens
  • STD now has in a q-like sublanguage for tr/// string parsing
  • implements the MONKEY_TYPING constraint on augment and supersede declarators
  • various random cleanups and bugfixes
  • added Z metaoperator
  • lots of works on regex flags to unify them into a single %*RX structure at parse time
  • makes it easier to do all of the lexical scoping in parallel
  • can now remap run-time's $?FOO variables to parser's $*FOO dynamic variables
  • otherwise, bugfixes, spec cleanup, and test cleanup

Allison:

  • working on tickets
  • updating the Parrot roadmap to match our Rakudo Star support plan
  • working on the mini-language in NQP for a class assignment
  • found a new Pynie developer who saw my talk at Pycon
  • may be doing a Summer of Code project in it
  • answering lots of questions on IRC and helping out with ideas

c:

  • working on lots of little bugs for Parrot
  • should have the method namespace bug fixed, with help from Andrew
  • exploring some optimization possibilities
  • should be able to merge the PCC refactor shortly
  • Allison, see TT #1511

Allison:

  • we need to add a new opcode, something like set_want
  • call it to update the CallContext with expected return information

c:

  • works a bit like Perl 5 there
  • we could use that information for MMD, that'd be interesting
Monday March 22, 2010
08:37 PM

Perl 6 Design Minutes for 10 March 2010

The Perl 6 design team met by phone on 10 March 2010. Larry, Allison, Patrick, Jerry, Will, and chromatic attended.

Larry:

  • scrapped @array[%100_000] modular subscript notation in favor of a more general mapping closure
  • put back :s file test, removed :z, :T, :B, :M, :A, :C
  • clarified that these are defined on IO, not on strings
  • deprecated the {*} and #= reduction stub notations in grammars
  • attributive parameters now default to is copy binding; but easy for an attribute to override this with is ref
  • tried to move operator definitions to CORE; found one approach that doesn't work and abandoned it
  • STD now allows _ in numeric variable names like $10_000.
  • factored out curlycheck so we can use it on any trailing curly
  • postcircumfix:<{ }> now uses curlycheck for consistency
  • STD now speculates missing semicolon when two terms in a row are separated by at least one newline
  • removed mention of *.notdef in favor of :!defined
  • still need to remove it from the spec though
  • ambiguously rebound outer lexicals now detected even if ambiguity propagates from an inner scope
  • reports more pertinent information in that case so the difficulty can be understood by the user
  • various random debugger refactorings
  • properly scope dynamic package names for block-oriented packages to include name declaration
  • package_def of ; packages now eats statementlist itself to stay inside proper scope
  • much work on package qualified names
  • correctly parse <$x> part of FOO::<$x> as part of variable name
  • correctly follow symbolically indirected OUTER:: links
  • find_top_pkg no longer cares if name ends in ::
  • STD now figures out whether initial components lead to package or lexical scope
  • no longer scans outer scopes on qualified names
  • now handles FOO::<$x> form in check_variable
  • no longer checks for @/% mistakes on qualified names

Patrick:

  • haven't had much hacking time lately due to personal demands
  • should be able to hack again later today and the rest of the week

Allison:

  • worked on the PCC refactor
  • that went well; the hackathon was good
  • it didn't pull in a lot of people, but me dedicating the weekend to it was helpful
  • also pulled in a few other people willing to try things out
  • we made good progress
  • our initial task is over
  • we're in the nebulous stage of debugging
  • need to review a change in optional return values
  • also worked on Ubuntu and Debian packaging
  • Parrot 2.0 is in both
  • it'll be in April's Lucid Lynx Ubuntu

Jerry:

  • Google Summer of Code is starting
  • TPF and PaFo are teaming up this year
  • we're working on the organization application
  • Jonathan Leto is leading things and I'm backing him up
  • we're looking for mentors and ideas; see the TPF GSoC wiki page

Will:

  • started going through Rakudo's RT queue
  • did more Parrot building and cleanup work
  • no longer invoking Perl to invoke the C compiler for each build file
  • shaved some time off the build
  • eliminated one recursive make, leaving two
  • then I can remove more things from config

c:

  • worked on a bunch of branches
  • fixed a couple of bugs
  • hope to get more bug fixing time in
Saturday March 13, 2010
06:19 PM

Perl 6 Design Minutes for 03 March 2010

The Perl 6 design team met by phone on 03 March 2010. Larry, Allison, Patrick, Jerry, Will, and chromatic attended.

Larry:

  • noted how lastcall allows nextsame control of nested dispatchers
  • reserved the final paren-based shape declaration syntax without committing to it meaning anything
  • clarified that Nil itself is defined but likes to produce undefined values when indexed
  • added some clarifications of how the series operator deals with type information
  • clarified that Pair.ACCEPTS uses "so" and "not" semantics so :s returns True or False
  • removed the 1/2 and +2-3i literal forms, now rely on angle forms <1/2> and <+2-3i> for literals, and the bare forms now rely on constant folding rather than a fragile special syntax
  • in STD, made undeclared variables more fatal
  • STD now tries to be helpful if the user makes the typical P5-ish variant-sigil mistake on arrays and hashes
  • also improved error message on the -{}> kind of mistake that P5 programmers will make
  • my $a, $b now gives better message
  • STD now reserves the () shape syntax per current spec
  • fixed regression on indirect method knowing that method name is not bound early
  • moved unexpected-!! panic from infixstoppers to infix:<!!> for better extensibility
  • so a user's infix definition isn't ignored if it starts with !!
  • you can define user operators starting with that, and it only complains for the right reasons now
  • STD now gives an accurate message when a prefix is missing its term
  • removed deprecated rational and complex literal forms from STD
  • much preliminary work for moving operator defs to CORE.setting, not yet checked in
  • only blocker is not being in Copenhagen

Patrick:

  • Jonathan, Carl, Moritz, and Martin will be there
  • I proposed a panel discussion instead of my talk on Tuesday afternoon at 3 pm
  • I'll be online then
  • can't make it due to sudden personal reasons
  • will be online quite a bit the next few days though
  • can participate in the hackathon remotely
  • worked mostly on helping other people get their tasks done
  • updated the parser to handle more operator conditions
  • working toward enabling user-defined operators
  • quite a few new people submitted patches
  • several were non-trivial
  • one patch put grammars, regexes, and tokens back in Rakudo
  • that's not trivial and it worked pretty well
  • I'm reviewing patches and making comments
  • lots of good progress
  • expect lots more during the hackathon

Allison:

  • going to work on code stuff this weekend instead of traveling
  • had a very productive trip
  • glad to be home to get work done
  • working on the PCC branch this week
  • should be, fingers crossed, small and easy to get done
  • want to avoid creature feeping
  • get the re-ordering through and move on

Jerry:

  • having trouble building Rakudo on Windows
  • have time to debug with people online
  • this is preventing me from talking to Patrick about and working on S19

Patrick:

  • we can work on that tomorrow

Will:

  • saw that problem on p6c as well
  • fixed a Parrot bug for Patrick related to STRING indices
  • we have some speed fixes on top of that
  • still working on the build cleanup
  • hope to merge to trunk in the next two or three days

c:

  • haven't had and won't have much time
  • fixed a few bugs
  • working on helping other people get stuff done

Jerry:

  • is there a hackathon or meeting time available after OSCON?

Allison:

  • recommend the weekend after

Patrick:

  • there'd have to be a hackathon for me to get TPF sponsorship

Jerry:

  • the pace of spec changes has picked up
  • any ideas what's driving that?
  • is it different from before?
  • was the end-of-year lull the same as before?

Larry:

  • everyone did take a break over Christmas
  • most of the changes are still simplifications
  • or responses to implementation issues
  • dealing with inconsistencies

Patrick:

  • a lot of implementation issues have come up over the past three weeks

Larry:

  • ng has flushed out a lot of design issues

Jerry:

  • that's great!

Patrick:

  • that's great for Larry, but I have a deadline!

Allison:

  • remember, it's a stake in the ground
  • "This is a release of Perl 6 you can use NOW!"

Patrick:

  • we're driving the spec with regard to lists and arrays

Larry:

  • they essentially have the same structure
  • they need separate typology
  • you need to know whether to clone an iterator
  • that's the only reason you have to know

Patrick:

  • did you see my comment about binding being the distinguishing feature?

Larry:

  • I think about that in inside out terms
  • not sure I can put that in words yet
  • had a conversation with Solomon about the FP view of iterators and arrays
  • that's some of my thinking
  • do we promise to hold a pointer fixed, or go on to the next thing?
  • whether that thing is persistent is mostly the bailiwick of the GC, from the standpoint of the language

Patrick:

  • I wasn't sure how that applied to my specific context
  • maybe I should work up a description of words or implementation
  • some lists I want to keep around reified elements
  • some lists I don't
  • the distinction is whether it's bound to any variable

Larry:

  • may depend on what it's bound to
  • we might make the keeparound promise only for binding to @

Patrick:

  • I came up with binding to $ examples
  • we can get laziness but eat up a ton of memory
  • if we throw things away when iterating, we get more things wrong

Larry:

  • it's a matter of tracking
  • are we bound to something that tells the GC to keep the rest of the list around?
  • that's the FP view

Patrick:

  • that's not just a GC view
  • it's how people refer to them
  • my GC is taken care of by my virtual machine anyway
  • it's about reachability from the HLL
  • or did you see it disappear

Larry:

  • that's whether you have a reference to it

Patrick:

  • how do you know whether to keep a reference to it?
  • I've produced this element
  • can I send it back to the caller
  • or do I need to keep it around so something else can get to it
  • if the iterator itself is bound, you keep the reference
  • if it's not bound, you can return it but not keep the reference around
  • I'll write up my thoughts

Jerry:

  • will these changes settle down after Rakudo *?
  • are they a precursor to that release?
  • will they continue afterward?
  • will Rakudo * go stale?
  • that's a tough one to answer

Patrick:

  • I can't guarantee stability at this point
  • we want a useful release
  • we'd like not to have any deprecations after that point
  • given how implementations and applications drive implementations
  • Rakudo * exists to encourage people to develop applications
  • we've never made that stability an explicit goal for Rakudo *
  • we'll probably institute deprecation cycles when it comes out
  • we don't want to change the world out from under people
  • it doesn't represent a spec freeze
  • thinking of a separate distribution release from the compiler release
  • a three month stability cycle of releases for Rakudo *
  • a different point of view
  • any distribution release doesn't have to be tied to the newest compiler release
  • I see Rakudo * as a series of releases, not a single release
Tuesday March 02, 2010
12:12 AM

Perl 6 Design Minutes for 24 February 2010

The Perl 6 design team met by phone on 24 February 2010. Larry, Allison, Patrick, and chromatic attended.

Larry:

  • my work last week was almost entirely responsive to various discussions on irc and p6l, even when it doesn't seem like it
  • clarified that LEAVE-style phasers do not trip till after an exception is handled (and not resumed)
  • the implementation of take is specifically before unwinding even if implemented with a control exception
  • simplified series operator by moving generator function to the left side (any function on right side will now be a limiting conditional)
  • a * is no longer required to intuit the series on the left; the absence of generator before the ... operator is sufficient
  • first argument on the right of ... is now always a limiter argument
  • for convenience and consistency, added a new ...^ form to exclude a literal limiter from the generated series
  • unlike ranges, however, there is no leading exclusion ^... or ^...^
  • series is a list associative list infix, and each ... pays attention only the portion of the list immediately to its left (plus the limit from the right)
  • an "impossible" limit can terminate a monotonic intuited series even if the limit can never match exactly
  • variables now default to a type of Any, and must explicitly declare Mu or Junction type to hold junctions
  • this is to reduce pressure to duplicate many functions like == with Mu arguments; most of our failure values should be derived from Any in any case
  • a Mu result is more indicative of a major malfunction now, and is caught at first assignment to an Any variable
  • Instant/Duration types are biased away from Num and towards Rat/FatRat semantics
  • Instant is now completely opaque; we no longer pretend to be the same as TAI, numerically speaking
  • Instants are now considered a more basic type than epochs, which are just particular named instants
  • all culturally aware time can be based on calculations involving instants and durations
  • list associative operators now treat non-matching op names as non-associative rather than right-associative, forcing parens
  • Whatever semantics now autocurry any prefix, postfix, or infix operator that doesn't explicitly declare that it handles whateverness itself
  • WhateverCode objects now take a signature to keep clear how many args are not yet curried
  • so *+* is now more like WhateverCode:($x,$y)
  • autocurrying is still transitive so multiple ops can curry themselves around a *
  • added semilists as Slicel type to go with Parcel
  • this allows us to bind @array[1,2,3] differently from @array[1,2,3;4,5,6], for instance
  • the Matcher type now excludes Bool arguments to prevent accidental binding to outer $_ when closure is needed
  • when and ~~ will now warn of always/never matching on direct use of True or False names as matcher
  • STD generalizes \w lookahead to all twigils now
  • STD now treats non-matching list associatives as non-associative
  • things like 1 min 2 max 3 are now illegal, and require parenthesization for clarity
  • STD now treat invocant colon as just a comma variant so it does not fall afoul of the list associativity change
  • CORE now recognizes the TrigBase enumeration

Patrick:

  • first release of the new branch of Rakudo last week
  • passing ~25,000 tests at the release
  • thanks to optimizations from chromatic, Jonathan, and Vasily, Rakudo has a lot of speed improvements
  • in particular, it can run those tests in under 10 minutes, non-parallel, depending on your hardware
  • older releases took 25 minutes and more
  • the regex tests will slow things down
  • ultimately, we're seeing a big speed improvement over the past releases
  • cleaned up lists and slices, now they work pretty well
  • worked with Solomon Foster and others to speed up trig operations
  • fixed a bug related to lexicals declared in classes
  • fixed the long-standing and often recurring problem with curlies ending a line/statement causing the next statement to be a statement modifier
  • easy to fix in the new grammar
  • that was nice
  • made an initial implementation of the sort method
  • it's very short, because Parrot provides one
  • there are a few bugs in Rakudo there still, but I'll get them
  • planning for the Copenhagen hackathon on March 5 - 9
  • Jonathan and I have been updating the Rakudo roadmap
  • will check that in in the next couple of hours
  • so far, every time we review it, we surprise ourselves at how much we've accomplished
  • we're meeting all of the top priority goals without making any heroic efforts
  • we'll put those goals in as well as timelines
  • most of the major tasks from previous roadmaps have happened

Allison:

  • working on Python this week
  • attended Python VM summit, Python language summit, and PyCon
  • Parrot's on good track to support what Python needs
  • useful to make community connections
  • when I reviewed Pynie, I was surprised to see how close it is to supporting the whole Python syntax
  • some of those features are big, like objects
  • but we should support them soon
  • Debian packages delayed by the absence of a sponsor
  • they should go into Debian soon though
  • I put in a request for feature-freeze exception for Ubuntu 10.4
  • Parrot 2.0 should go in
  • haven't made any commits to the PCC branch
  • that'll be a top priority for next week

c:

  • fixed a Parrot GC bug for last week's Rakudo release
  • made some optimizations in Rakudo and Parrot
  • helped Jonathan find a few more
  • fixed a long-standing math MMD bug
  • still working on HLL subclassing; more tricky than you think
  • may be some conflicting design goals about vtable overriding and MMD

Allison:

  • Patrick, do we need an explicit deprecation for old PGE and NQP?

Patrick:

  • I think Will already added one for NQP
  • we can add one for PGE if we need
  • they don't necessarily have to disappear at the next release
  • but no one's planning to maintain them

Allison:

  • no reason not to put in the notice now
  • we don't have to remove them at the earliest possible date
Wednesday February 24, 2010
07:27 PM

Perl 6 Design Minutes for 17 February 2010

The Perl 6 design team met by phone on 17 February 2010. Larry, Allison, Patrick, and chromatic attended.

Larry:

  • much work clarifying relationship of parcels to everything else (<a b>, assignment, arguments, captures, parameters, signatures, gather/take, and loop returns)
  • we now list all scope declarators in one spot
  • conjectured some ideas on how to handle the allomorphism of literals more dwimmily
  • had already specced some of this behavior for literals found inside qw angles.
  • literals that exceed a Rat64's denominator automatically keep the string form around for coercion to other types
  • clarified that anon declarator allows a name but simply doesn't install it in the symbol table
  • respecced the trig functions to use a pragma to imported fast curried functions
  • still uses enum second argument for the general case (rakudo is still stuck on slow strings there)
  • on iterators, renamed .getobj to .getarg since arguments are the typical positional/slicey usage
  • signatures are never bound against parcels anymore, only against captures
  • we now use "argument" as a technical term meaning either a real parcel or an object that can be used independent of context as an argument
  • anything that would stay discrete when bound to a positional, basically
  • return, take, and loop return objects are also arguments in that sense
  • they all return either a parcel or anything that can stand on its own as an argument
  • STD now adds a shortname alias on adverbialized names, ignores collisions on the shortname for now, which is okay for multis
  • STD now complains about longname (adverbialized) collisions
  • STD no longer carps about duplicate anonymous routine declarations
  • made the undeclared type message the same for parameters as for other declarations
  • clarify the error message about anonymous variables
  • no longer report a $) variable error where ) is the $*GOAL
  • add WHAT etc. to list of functions that require an argument

Allison:

  • working on two HLL implementations
  • one is Pynie, the other is Camle
  • nothing to do with Caml or ML
  • I've noticed huge improvements in NQP-rx from the previous NQP
  • can't say which feature improvements make the most difference, but I'll migrate Pynie pretty soon to take advantage of the new version
  • continuing to shepherd Debian and Ubuntu packages

Patrick:

  • essentially all I did was unify things
  • previously it had been two or three tools
  • it's just one

Allison:

  • even the syntax seems more regular

Patrick:

  • there are more pieces available in NQP-rx
  • Rakudo's -ng is now master
  • the old master is now -alpha
  • we took a big hit on spectests, but they seem to be coming back quickly
  • 5000 tests pass on trunk now
  • we have 16k or 17k we haven't re-enabled; they make the spectest slower
  • Jonathan thinks we may pass 25,000 tests now
  • that's great, considering where we were a week ago
  • I redid Rakudo's container, value, and assignment module
  • previously variables held values directly
  • now they contain reference PMCs
  • that cleaned up many things
  • we use more PMCs, but now we don't clone and copy as much
  • we move references around more
  • seems closer to how Perl 6 handles things
  • was much easier than I expected
  • updated the NQP-rx regex engine and built in constant types
  • handles Unicode character names
  • reclaims plenty of tests
  • answered lots of questions for people adding things into Rakudo
  • prioritizing other people writing code over writing code
  • increases our developer pool; seems to be working well
  • new release of Rakudo planned for tomorrow
  • don't know how many tests we'll pass, but it should go well
  • plan to put in a few things like sort and grammars over the next week
  • then I'll review the RT queue to find bugs and (hopefully) closeable bugs

c:

  • working on GC tuning
  • also working on String PMC tuning
  • working on built-in types and their behavior as classes and parent classes
  • the multidispatch bugs in particular I hope to solve