OReilly perl 6 and parrot essentials 2nd edition jun 2004 ISBN 059600737x

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TableofContents
Index
Reviews
ReaderReviews
Errata
Academic

Perl6andParrotEssentials,2ndEdition
ByAllisonRandal,DanSugalski,

LeopoldTötsch

Publisher :O'Reilly
PubDate :June2004
ISBN :0-596-00737-X
Pages :294


Thisbookisanunparalleledsneak-peekof
what'scominginthewidely-anticipatedPerl
6.Ituncoversgroundbreakingnew
developmentsinParrot--theinterpreter

enginethatwillexecutecodewritteninthe
newPerl6languageandthemost
revolutionarychangeinthelanguageitself-Apocalypse12onobjects.Italsoincludes


expandedcoverageofApocalypse5(regular
expressions)andApocalypse6(subroutines).



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•
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TableofContents
Index
Reviews
ReaderReviews
Errata
Academic

Perl6andParrotEssentials,2ndEdition
ByAllisonRandal,DanSugalski,

LeopoldTötsch

Publisher :O'Reilly
PubDate :June2004
ISBN :0-596-00737-X
Pages :294



Copyright

Preface
HowThisBookIsOrganized

FontConventions




UsingCodeExamples
We'dLiketoHearfromYou

Acknowledgments


Chapter1.ProjectOverview
Section1.1.TheBirthofPerl6




Section1.2.IntheBeginning...

Section1.3.TheContinuingMission


Chapter2.ProjectDevelopment
Section2.1.LanguageDevelopment





Section2.2.ParrotDevelopment


Chapter3.DesignPhilosophy
Section3.1.LinguisticandCognitiveConsiderations

Section3.2.ArchitecturalConsiderations


Chapter4.BasicSyntax
Section4.1.Variables

Section4.2.Operators

Section4.3.ControlStructures


Chapter5.Subroutines
Section5.1.UsingSubroutines

Section5.2.Parameters




Section5.4.SubroutineStubs




Section5.6.AnonymousSubroutines




Section5.8.CurriedSubroutines




Section5.10.LvalueSubroutines

Section5.3.Arguments
Section5.5.SubroutineScope
Section5.7.MultiSubroutines
Section5.9.WrappedSubroutines
Section5.11.Macros

Chapter6.Objects
Section6.1.UsingObjects

Section6.2.Classes




Section6.3.Roles




Section6.5.PrivateandPublic




Section6.7.Submethods

Section6.4.Delegation
Section6.6.Subroutines
Section6.8.MultipleDispatch


Chapter7.GrammarsandRules
Section7.1.UsingRules

Section7.2.BuildingBlocks




Section7.3.Modifiers




Section7.5.BacktrackingControl

Section7.4.Built-inRules
Section7.6.HypotheticalVariables


Chapter8.ParrotInternals
Section8.1.CoreDesignPrinciples

Section8.2.Parrot'sArchitecture



Section8.3.TheInterpreter

Section8.4.I/O,Events,andThreads




Section8.6.AdvancedFeatures

Section8.5.Objects
Section8.7.Conclusion


Chapter9.ParrotAssemblyLanguage
Section9.1.GettingStarted

Section9.2.Basics




Section9.3.WorkingwithPMCs




Section9.5.StacksandRegisterFrames




Section9.7.Subroutines

Section9.9.Events




Section9.11.LoadingBytecode

Section9.4.FlowControl
Section9.6.LexicalsandGlobals
Section9.8.ExceptionsandExceptionHandlers
Section9.10.Threads
Section9.12.ClassesandObjects

Section9.13.WritingTests


Chapter10.ParrotIntermediateRepresentation
Section10.1.Statements




Section10.2.VariablesandConstants

Section10.4.Labels




Section10.6.Subroutines

Section10.3.SymbolOperators
Section10.5.FlowControl
Section10.7.Methods


Chapter11.ParrotReference
Section11.1.PASMOpcodes

Section11.2.PIRDirectives






Section11.3.PIRInstructions
Section11.4.ParrotCommand-LineOptions
Colophon
Index


Copyright©2004,2003O'ReillyMedia,Inc.

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Preface
Thereisnothingasscarytotheaverageprogrammer(tothe
averagehuman,really)asthesingleword"change."Change
meanstakingthetimetolearnanewwayofdoingthings.
Changescanbeannoying:movingtoanewhome,findingthe
shelvesreorganizedatyourneighborhoodcomputerstore,or
orderingyourfavoritebeeratyourfavoritepubonlytobetold

theydon'tmakeitanymore.Butchangescanalsobegood:a
vacationonthebeach,apromotion,araise,findingtheperfect
shortcuttoworkthatshaves20minutesoffyourcommute.This
bookisallaboutchange...thegoodkind.
Perl6isn'tfarenoughalongtosupportabookonthelevelof
ProgrammingPerl.However,asdevelopmentgoeson,we've
foundthattheaccumulatedloreofthepastfewyearsisquite
anentrybarrierfornewpeople.Thisbookisasnapshotofthe
currentstatus,designedtoeasethatfirststep.Itcoversthe
projectthroughApocalypse12andthe0.1.0releaseofParrot.
Weexpectthatthiswillbethelasteditionofthebook,butwe
willpublishupdatesasneeded.


HowThisBookIsOrganized
Thisbookhas11chapters:
Chapter1isahigh-leveloverviewoftheproject,withsome
historyofhowandwhytheprojectwasstarted.
Chapter2providesmoredetailonlifecycleswithintheproject
andhowtogetinvolved.
Chapter3explainssomeoftheprinciplesbehindPerl6design
work.
Chapter4-Chapter7areanintroductiontoPerl6syntax.
Chapter8explainstheoverallarchitectureofParrot(thevirtual
machinethatrunsPerl6).
Chapter9isanintroductiontoParrotassemblylanguage.
Chapter10isanintroductiontoParrotintermediate
representation.
Chapter11isareferenceforParrotassemblylanguage,Parrot
intermediaterepresentation,andcommand-lineoptionsforthe

Parrotinterpreter.
Ifyou'reaPerlprogrammerwhoiscompletelynewtoPerl6,
you'llbeinterestedinthisbooktogetanideaofwhatit'llbe
liketoworkwithPerl6,whywe'remakingthechangeswe're
making,andhowtheprojectisgoing.You'llwanttoreadthe
firstsevenchapters.Ifyouthinkyoumightbeinterestedin
gettinginvolvedinimplementation,readtherestaswell.
Ifyou'realreadyinvolvedinthePerl6project,you'llbe
interestedinthisbooktoseehowallthepiecesfittogether,and
youmaywanttouseitasareferencewhileyou'reworking.If


you'vebeeninvolvedonlyonthelanguagesideortheinternals
side,you'llalsogetachancetoseewhattheotherhalfis
doing.Inthisway,theentirebookisrelevanttoyou.
Ifyou'reinterestedinimplementinganotherlanguageontopof
Parrot,you'llwanttoskimthroughtheParrotinformationin
Chapter2,andthenskipstraighttoChapter8andgofrom
there.
Ifyou'renotinvolvedinPerlbutjustwanttoseewhatthe"Perl
6"buzzisallabout,you'llwanttoreadChapter1,Chapter3,
andChapter8.You'llgetanoverviewofwhatwe'redoingand
why,withoutallthenitty-grittydetails.


FontConventions
Thefollowingfontconventionsareusedinthisbook:

Italic
Usedforfilenames,exampleURLs,andexampleemail

addresses

Constantwidth
Usedincodelistingsandforfunctionnames,variable
names,andotherliteraltext

Constantwidthitalic
Showstextthatshouldbereplacedwithuser-supplied
values


UsingCodeExamples
Thisbookisheretohelpyougetyourjobdone.Ingeneral,you
mayusethecodeinthisbookinyourprogramsand
documentation.Youdonotneedtocontactusforpermission
unlessyou'rereproducingasignificantportionofthecode.For
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Incorporatingasignificantamountofexamplecodefromthis
bookintoyourproduct'sdocumentationdoesrequire
permission.
Weappreciate,butdonotrequire,attribution.Anattribution
usuallyincludesthetitle,author,publisher,andISBN.For
example:"Perl6andParrotEssentials,SecondEdition,by
AllisonRandal,DanSugalski,andLeopoldTötsch.Copyright
2004O'ReillyMedia,Inc.,0-596-00737-X."
Ifyoufeelyouruseofcodeexamplesfallsoutsidefairuseor

thepermissiongivenabove,feelfreetocontactusat



We'dLiketoHearfromYou
Pleaseaddresscommentsandquestionsconcerningthisbookto
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Acknowledgments
Manythankstoourreviewersforthiseditionofthebook:Leon
Brocard,PiersCawley,DamianConway,chromatic,JeffreyDik,
SimonGlover,GarrettGoebel,TreyHarris,GregorPurdy,
JérômeQuelin,JensRieks,BrentRoyal-Gordon,JosephRyan,
HugovanderSanden,andMelvinSmith.

ThisbookisdedicatedtothePerlcommunity,becauseit
wouldn'texistwithoutthem.


Chapter1.ProjectOverview
Perl6isthenextmajorversionofPerl.It'sacompleterewrite
oftheinterpreter,andasignificantupdateofthelanguage
itself.ThegoalofPerl6istoaddsupportformuch-needednew
features,andstillbecleaner,faster,andeasiertouse.
ThePerl6projectisvastandcomplex,butitisn'tcomplicated.
Theprojectrunsonasimplestructurewithverylittle
managementoverhead.That'sreallytheonlywayitcouldrun.
Theprojectdoesn'thavehugecashortimeresources.Itsonly
resourceisthepeoplewhobelieveintheprojectenoughto
spendtheiroff-hourstheir"relaxation"timeworkingtoseeit
completed.Thischapterisasmuchaboutpeopleasitisabout
Perl.


1.1TheBirthofPerl6
BackonJuly18,2000,theseconddayofthefourthPerl
Conference(TPC4),asmallbandofPerlgeeksgatheredto
prepareforameetingofthePerl5Porterslaterthatday.The
topicathandwasthecurrentstateofthePerlcommunity.Four
monthshadpassedsincethe5.6.0releaseofPerl,andalthough
itintroducedsomeimportantfeatures,nonewererevolutionary.
Therehadbeenverylittleforwardmovementintheprevious
year.ItwasgenerallyacknowledgedthatthePerl5codebase
hadgrowndifficulttomaintain.Atthesametime,infightingon
theperl5-porterslisthadgrownsointensethatsomeofthe

bestdevelopersdecidedtoleave.Itwastimeforachange,but
noonewasquitesurewhattodo.Theystartedconservatively
withplanstochangetheorganizationofPerldevelopment.
Anhourintothediscussion,aroundthetimemostpeoplenod
offinanymeeting,JonOrwant(thereserved,universally
respectededitorofthePerlJournal)steppedquietlyintothe
roomandsnappedeveryonetoattentionwithanentirely
uncharacteristicandwell-plannedgesture.Smash!Acoffee
mughitthewall."Weare*@$!-ed(Crash!)unlesswecan
comeupwithsomethingthatwillexcitethecommunity(Pow!),
becauseeveryone'sgettingboredandgoingoffanddoingother
things!(Bam!)"(Atleast,that'sbasicallyhowLarrytellsit.Asis
usuallythecasewitheventslikethis,nooneremembers
exactlywhatJonsaid.)
Awakenedbythisdisplay,thegroupstartedtosearchforareal
solution.Thelanguageneededroomtogrow.Itneededthe
freedomtoevaluatenewfeatureswithouttheobscuringweight
oflegacycode.Thecommunityneededsomethingtobelievein,
somethingtogetexcitedabout.
WithinafewhoursthegroupsettledonPerl6,acomplete


rewriteofPerl.Theplanwasn'tjustalanguagechange,justan
implementationchange,orjustasocialchange.Itwasa
paradigmshift.Perl6wouldbethecommunity'srewriteofPerl,
andthecommunity'srewriteofitself.
WouldPerl6,particularlyPerl6asacompleterewrite,have
happenedwithoutthismeeting?Almostcertainly.Thesigns
appearedonthelists,inconferences,andinjournalsmonthsin
advance.Ifithadn'tstartedthatday,itwouldhavehappeneda

weeklater,orperhapsafewmonthslater,butitwouldhave
happened.Itwasastepthecommunityneededtotake.


1.2IntheBeginning...
Let'spauseandconsiderPerldevelopmentuptothatfateful
meeting.Perl6isjustanotherlinkinthechain.Themotivations
behinditandthedirectionsitwilltakearepartiallyguidedby
history.
Perlwasfirstdevelopedin1987byLarryWallwhilehewas
workingasaprogrammerforUnisys.Aftercreatinga
configurationandmonitoringsystemforanetworkthat
spannedthetwoAmericancoasts,hewasfacedwiththetaskof
assemblingusablereportsfromlogfilesscatteredacrossthe
network.Theavailabletoolssimplyweren'tuptothejob.A
linguistatheart,Larrysetouttocreatehisownprogramming
language,whichhecalledperl.Hereleasedthefirstversionof
PerlonDecember18,1987.Hemadeitfreelyavailableon
Usenet(thiswasbeforetheInternettookovertheworld,
remember),andquicklyacommunityofPerlprogrammers
grew.
TheearlyadoptersofPerlweresystemadministratorswhohad
hitthewallwithshellscripting,awk,andsed.However,inthe
mid-1990sPerl'saudienceexplodedwiththeadventoftheWeb,
asPerlwastailor-madeforCGIscriptingandotherweb-related
programming.
Meantime,thePerllanguageitselfkeptgrowing,asLarryand
otherskeptaddingnewfeatures.Probablythemost
revolutionarychangeinPerl(untilPerl6,ofcourse)wasthe
additionofmodulesandobject-orientedprogrammingwithPerl

5.AlthoughthismadethetransitionperiodfromPerl4toPerl5
unusuallylong,itbreathednewlifeintothelanguageby
providingamodern,modularinterface.BeforePerl5,Perlwas
consideredsimplyascriptinglanguage;afterPerl5,itwas
consideredafull-fledgedprogramminglanguage.


Larry,meanwhile,startedtakingabackseattoPerl
developmentandallowedotherstotakeresponsibilityfor
addingnewfeaturesandfixingbugsinPerl.ThePerl5Porters
(p5p)mailinglistbecamethecentralclearinghouseforbug
reportsandproposedchangestothePerllanguage,withthe
"pumpkinholder"(alsoknownasthe"pumpking")beingthe
programmerresponsibleforintegratingthepatchesand
distributingthemtotherestofthelistforreview.Larry
continuedtofollowPerldevelopment,butlikeaparent
determinednottosmotherhischildren,hestayedoutofthe
day-to-daydevelopment,limitinghisinvolvementtosituations
inwhichhewastrulyneeded.
AlthoughyoumightthinkthatthebirthofthePerl6project
wouldbethefirstnailinthecoffinforPerl5,that'sfarfromthe
case.Ifanything,Perl5hashadahugeresurgenceof
development,withPerl5.7.0releasedonlytwoweeksafterthe
initialdecisiontogoaheadwithPerl6.Perl5.8.0,aJuly2002
releasebypumpkingJarkkoHietaniemi,includesusable
Unicodesupport,aworkingthreadsinterface,safesignals,and
asignificantimprovementoftheinternalswithcodecleanup,
bugfixes,betterdocumentation,andmorethanquadrupled
testcoverage.5.8hasquarterlymaintenancereleasesthanks
topumpkingNicholasClark.The5.9-5.10releaseshaveHugo

vanderSandenasarchitectandRafaëlGarcia-Suarezas
pumpking.Plansforthosereleasesincludeenhancementsto
theregularexpressionengine,furtherinternalscleanupanda
"useperl6ish"pragmathatwillintegratemanyofthefeatures
ofPerl6.Perl5isactiveandthriving,andwillcontinuetobeso
evenafterthereleaseofPerl6.0.


1.3TheContinuingMission
Muchhaschangedsincetheearlydaysoftheproject.New
peoplejoinandothersleaveinaregular"changingofthe
guard"pattern.Planschangeastheworkprogresses,andthe
demandsoftheworkandtheneedsofthecommunitybecome
clearer.TodaythePerl6projecthastwomajorparts:language
designandinternals.Eachbranchisrelativelyautonomous,
thoughthereisahealthyamountofcoordinationbetween
them.

1.3.1LanguageDesign
AswithallthingsPerl,thecentralcommandofthelanguage
designprocessisLarryWall,thecreatorofthePerllanguage.
Larryissupportedbytherestofthedesignteam:Damian
Conway,AllisonRandal,DanSugalski,HugovanderSanden,
andchromatic.Wespeakinweeklyteleconferencesandalso
meetface-to-faceafewtimesayeartohashoutideasforthe
designdocuments,ortoworkthroughroadblocksstandingin
thewayofdesignorimplementation.Thedesignteamisa
diversegroup,includingprogrammers-for-hire,Perltrainers,
andlinguistswithabroadspectrumofinterestsand
experiences.Thisdiversityhasprovedquitevaluableinthe

designprocess,aseachmemberisabletoseeproblemsinthe
designorpotentialsolutionsthattheothermembersmissed.

1.3.1.1RequestsForComments(RFCs)
ThefirststepindesigningthenewlanguagewastheRFC
(RequestForComments)process.Thisspurredaninitialburst
ofcommunityinvolvement.AnyonewasfreetosubmitanRFC


onanysubject,whetheritwasassmallasaddinganoperator,
orasbigasreworkingOOsyntax.Mostoftheproposalswere
reallyquiteconservative.TheRFCsfollowedastandardformat
sotheywouldbeeasiertoreadandeasiertocompare.
EachRFCwassubjecttopeerreview,carriedoutinanintense
fewweeksaroundOctober2000.OnethingtheRFCprocess
demonstratedwasthatthePerlcommunitystillwasn'tquite
readytomovebeyondtheinfightingthathadcharacterizedPerl
5Portersearlierthatyear.[1]EventhoughfewRFCshavebeen
acceptedwithoutmodification,theprocessidentifiedalarge
numberofirritantsinthelanguage.Thesehaveservedas
signpostsforlaterdesignefforts.
[1]Mark-JasonDominuswroteanexcellentcritiqueoftheRFCprocess
(Itmayseemharshtopeopleaccustomed
tothemoreopenandtolerantcommunityoftoday,butit'sanaccuraterepresentationofthetime
whenitwaswritten.

1.3.1.2Apocalypses,Synopses,Exegeses
TheApocalypses,[2]Synopses,andExegeses[3]areanimportant
partofthedesignprocess.LarrystartedtheApocalypseseries
asasystematicwayofansweringtheRFCs.EachApocalypse

correspondstoachapterinhisbookProgrammingPerl,and
addressesthefeaturesinthechapterthatarelikelytochange.
[2]An"apocalypse"inthesenseof"revelation,"not"endoftheworld."

[3]An"exegesis"isanexplanationorinterpretationofatext.

However,theApocalypseshavebecomemuchmorethana
simpleresponsetoRFCs.Larryhasastartlingknackforlooking
at12solutionstoaproblem,pullingoutthegoodbitsfrom
eachone,andcombiningthemintoasolutionthatis10times
betterthananyoftheproposalsalone.TheApocalypsesarean
excellentexampleofthis"LarryEffect."Headdresseseach


relevantRFC,andgivesreasonswhyheacceptedorrejected
variouspiecesofit.ButeachApocalypsealsogoesbeyonda
simple"yes"and"no"responsetoattacktherootsofthe
problemsidentifiedintheRFCs.
TheSynopsesaresummariesofeachApocalypse.Theseactas
aquickreferenceforthecurrentstateofdesign,andaremore
approachablethantheoftenlengthyApocalypses.TheSynopsis
seriesdidn'tstartuntilApocalypse5,butLukePalmerisnow
workingontheretroactiveSynopses2-4.
DamianConway'sExegesesareextensionsofeachApocalypse.
TheExegesesarebuiltaroundpracticalcodeexamplesthat
applyandexplainthenewideas.

1.3.1.3Thep6lmailinglist
ThenextbodyofdesignworkisthePerl6Languagemailinglist
(),oftenfondlyreferredtoas"p6l."

PiersCawleywritesaweeklysummaryofallthePerl6mailing
lists.LukePalmerhasbeendeputizedasunofficialrefereeof
thelist.Heanswersquestionsthatdon'trequirethedirect
involvementofthedesignteamorthathavebeenanswered
before.Thelisthasapproximately40regularcontributorsin
anygivenmonth,aswellasalargenumberofoccasional
postersandlurkers.Somepeoplehaveparticipatedsincethe
verybeginning;othersappearforafewmonthsandmoveon.
Eventhoughtheindividualschange,thegeneraltoneofp6lis
thesame.It'sanopenforumforanyideasontheuser-visible
partsofPerl6.Inthetypicalpattern,onepersonpostsanidea
and5to10peoplerespondwithcriticismsorsuggestions.The
listperiodicallytravelsdownaspeculativethreadlikearunaway
train,buttheseeventuallyrunoutofsteam.ThenLarrypicks
outthegoldenbitsandgentlytellstherestthatno,henever
intendedPerl6tohaveneo-VulcanmechanoidScooby-Dooby-


doos.EvenwhenLarrydoesn'tpost,hefollowsthelistandthe
trafficservesasavaluablecatalystforhisthoughts.

1.3.2Internals
TheinternalsdevelopmentforPerl6fallstotheParrotproject.
TheheartofParrotisagrandioseideathatturnedouttobe
morerealisticthananyoneoriginallycouldhavebelieved:why
nothaveasingleinterpreterforseverallanguages?Unlikethe
parentPerl6project,whichwaslaunchedinasingleday,the
planforParrotformedinbitsandpiecesovertheperiodofa
year.
OnApril1,2001,SimonCozenspublishedanarticletitled

"ProgrammingParrot"asanAprilFools'joke
(Itwasa
contrivedinterviewwithLarryWallandGuidovanRossum
detailingtheirplanstomergePythonandPerlintoanew
languagecalledParrot.Afewmonthslater,whenPerl6
internalsbegantotakeanindependentpathwithinthelarger
project,theydubbedthesubproject"Parrot"inafittingturnof
lifeimitatingart.


EarlyStepsTowardPerl6Internals
TheearliestprogresstowardimplementingPerl6startedbeforethecurrent
incarnationofPerl6wasevenconceived.TheTopazproject,startedin1998,
wasspearheadedbyChipSalzenberg.ItwasareimplementationofPerl5
writteninC++.Theprojectwasabandoned,butmanyofthegoalsandintended
featuresforTopazwereadoptedforPerl6internals,andthedifficultiesTopaz
encounteredwerealsovaluableguides.
SapphirewasanotherearlyprototypethatinfluencedtheshapeofPerl6
internals.Itwasaone-weekprojectinSeptember2000.ThebrainchildofSimon
Cozens,SapphirewasanotherrewriteofPerl5internals.Itwasneverintended
forrelease,onlyasanexperimenttoseehowfartheideacouldgoinaweek,
andwhatlessonscouldbelearned.

TheplanforParrotwastobuildalanguage-neutralrun-time
environment.Itwouldsupportallthefeaturesofdynamic
languages,suchasPython,Ruby,Scheme,Befunge,and
others.ItwouldhavethreadingandUnicodesupport(twoof
themostproblematicfeaturestoaddintoPerl5code)designed
infromthestart.Itwouldsupportexceptionsandcompilation
tobytecode,andhavecleanextensionandembedding

mechanisms.
Thelanguage-neutralinterpreterwasoriginallyjustasideeffect
ofgooddesign.Keepingtheimplementationindependentofthe
syntaxwouldmakethecodecleanerandeasiertomaintain.
OnepracticaladvantageofthisdesignwasthatParrot
developmentcouldbegineventhoughthePerl6language
specificationwasstillinflux.
Thebiggerwininthelongterm,though,wasthatsinceParrot
wouldsupportthefeaturesofthemajordynamiclanguagesand
wasn'tbiasedtoaparticularsyntax,itcouldrunallthese
languageswithlittleadditionaleffort.It'sgenerally
acknowledgedthatdifferentlanguagesaresuitedtodifferent


tasks.Pickingwhichlanguagewillbeusedinalargesoftware
projectisacommonplanningproblem.There'sneveraperfect
fit.Itusuallyboilsdowntopickingthelanguagewiththemost
advantagesandtheleastnoticeabledisadvantages.Theability
toeasilycombinemultiplelanguageswithinaprojectcouldbea
hugebenefit.Usewell-testedlibrariesfromonelanguagefor
onetask.Takeadvantageofacleanwayofexpressinga
particularproblemdomaininasecond,withoutbeingforcedto
useitinareaswhereit'sweak.
Themodulardesignalsobenefitsfuturelanguagedesigners.
Insteadoftargetinglex/yaccandreimplementinglow-level
featuressuchasgarbagecollectionanddynamictypes,
designerscanwriteaparserthattargetstheParrotvirtual
machine.
DanSugalskileadstheParrotprojectaschiefarchitect,and
LeopoldTötschisthecurrentpumpking.TheParrotprojectis

largelyautonomous.Dancoordinateswiththerestofthedesign
teamtoensurethatParrotwillbeabletosupportthesemantics
Perl6willrequire,butthelanguagedesignershaveverylittle
inputintothedetailsofimplementation.Parrotisn'tdeveloped
solelyforPerl,butPerl6isentirelydependentonParrotitisthe
onlyinterpreterforPerl6.
ThecorecommunicationlinefortheParrotprojectisthe
mailinglist,,otherwiseknownas"
p6i."It'samuchmorebusiness-likelistthanp6l.Workflowin
Parrottakestheformofsubmittedpatches.Anyoneisfreeto
submitapatch,andcontributorswhoconsistentlysubmit
valuablepatchesoveralongperiodoftimearegrantedcheckinaccesstotheCVSrepository.

1.3.3Ponie
PonieisanimplementationofPerl5onParrot,startedinJuly


2003.Offically,Poniestandsfor"PerlOnNewInternalEngine."
Thenamewasoriginallyderivedfromarunninggaginthe
London.pmPerlMongersgroupwherethephrase"Iwanta
pony"appearedinlistsoffeaturerequestsforPerl(andother
unusualplaces).
Theproject,ledbyArturBergman,hastakenthePerl5source
codeasabaseandisgraduallyreplacingthecoreelements
withParrotequivalents.Legacycodewillbeoneofthebiggest
obstaclestoprojectsconsideringthemovefromPerl5toPerl6.
Fewcompanieshavetheresourcestodoacompleteupdateto
existingcodeeverytimeanewversionofthelanguageis
released.PonieoffersasmoothmigrationpaththatensuresPerl
5codewillfunctionaslongasit'sneeded.You'llevenbeableto

usePerl5modulesandPerl6modulesside-by-sideinthesame
program.ThecurrentplanisforPonietobethe5.14or5.16
releaseofPerl.
ThemailinglistforPoniedevelopmentis

1.3.4SupportingStructure
Last,butnotleast,isthegluethatholdstheprojecttogether.
AskBj rnHansenandRobertSpiermanagetheemail,revision
control,andbug-trackingsystems,aswellasthewebpagesfor
Perl6,Parrot,andPonie().Withoutthese
systems,theprojectwouldgrindtoascreechinghalt.
AllisonRandalistheprojectmanager.Asistypicalofopen
sourcedevelopmentprojects,managingthePerl6projectis
quitedifferentfrommanagingacommercialprojectofthesame
sizeandcomplexity.Therearenoschedules,nodeadlines,no
hiringandfiring,andnosalaries,bonuses,orstockoptions.
Therearenoemployeesorbosses;thereisverylittlehierarchy
whatsoever.Managementinthiscontextisn'taboutgiving
orders,it'saboutmakingsureeveryonehaswhattheyneedto