Perl 5.16 and Beyond - YAPC::Asia 2011

Perl 5.16 and beyondJesse Vincentjesse@perl.org@obra

Perl 6 Recovering Perl 6 Project Manager

Perl 5Perl 5 Pumpking

Perl 5Perl 5 Pumpking http://flic.kr/p/6StRmB

Perl 5Perl 5 Pumpking

?Whats a Pumpking?

I make decisions

( )(the unpopular ones)

I delegate

( ) (any real work)

I document

( )(process and policy)

I destress

( )(other people)

I’m a manager

Perl ?So, who makes Perl?

Many awesome people

I just standaroundlookingpretty...

...while other people do awesome stuff

Perl AUTHORS ? Is your name in Perl’s AUTHORS ﬁle?

CPAN ? Are you aCPAN author?

You rock

PerlYou make Perl

PerlThe rules ofPerl Club

commit e8cd7eae0498ecc1fd3801fe3160Author: Gurusamy Sarathy <gsar@cpan.org>Date: Sun Oct 10 23:48:07 1999 +0000add perlhack.pod from Nathan Torkington<gnat@frii.com>

1Rule 1

Perl Larry is always right about howPerl should behave

2Rule 2

Larry is allowed to change his mindabout any matter at a later date...

...regardless of whether he previouslyinvoked Rule 1

I’m not Larry

I’m nowhere near as clever

My shirts arenowhere near as loud

The rules aren’tjust for Larry

The rules aren’tjust for the Pumpking

Perl 5 The rules also apply to the Perl 5 core.

?What?

1Rule 1

PerlPerl is always right!

( ) (TMTOWTDI)

2Rule 2

Perl 5The Perl 5 coreis allowed to...

?change its mind?

Changing ourminds is easy

We are very good at it

Not ﬂailing wildly whenwe do has been hard

...and leads to problems

at least I haven’t heard this in a while...

PerlPerl is Dead !

PerlPerl is Dead !1!!

PerlPerl is Dead !1!!one!

What I’ve beenhearing lately...

?Where are we going?

It’s changing too fast.Can you slow down?

? You made regexescrazier? /$#@!/l?

smartmatch isn’tnamed correctly...

we should call it psychoticmatch

?Now that it’s undead,can we rename it?

I’ve been accused of lacking avision for Perl 5

WhatI lackis a ﬂame-proof suit http://en.wikipedia.org/wiki/File:Dance_Dance_Immolation.jpg

peWhat rl5I lack -po rt e rsis a ﬂame-proof suit http://en.wikipedia.org/wiki/File:Dance_Dance_Immolation.jpg

2 If I’d talked about myvision 2 years ago...

You would havelaughed at me

Perl 5 Improving Perl 5 did not matter

We couldn’t evenput out a new release

In the past year...

5 Five StableReleases

1 A dozendevelopment releases

Perl 5.14.2Perl 5.14.2 is thecurrent stablerelease of Perl 5

9It came out inSeptember

3 It used to take us3 weeks to prepare a release

We made thePumpking do it

1 Now it takesless than a day

43 The 43 step process is documented

We have rotatingrelease engineers

Many of them arenew committers

Release engineersneed commit bits

git Since the switch to git, we’ve nearly doubled our committer list

The worldhasn’t ended

Some of those releaseengineers have become proliﬁc contributors

Now thatreleasesare easy...

Perl 5A Vision for Perl 5

New versions of Perl 5should not breakyour existing software

Old syntax and semantics must not stopPerl 5 from evolving

Perl 5We need to be able to make mistakes as we rebuild Perl 5

We will make mistakesas we rebuild Perl 5

We have made mistakesas we’ve rebuilt Perl 5

We need to be able torecover from mistakes as we rebuild Perl 5

The runtime istoo big and must be slimmed down

Perl should havesane defaults

We need to be able to recover from lastyear’s “sane defaults”

Perl 5 Perl 5It should be possible to build more of Perl 5 in Perl 5

Perl should runeverywhere

2: Perl Rule 2:Perl is allowed to change its mind

That’s already true

That hurts programs and programmers

When your code runs, you have no ideawhat semantics it’ll see

use v5.14;

5.14 Perl ?“Can I have a Perl that’s 5.14 or newer?”

5.14.0 ! “Anything newer than 5.14.0 would be great!”

OK 5.30 ! “Ok. I’m 5.30. Have fun!”

That is not useful

It needs to change

Perl 5From now on, declare the version of Perl 5 you expect

use v5.16;

5.16 Perl 5 “I want a Perl 5 that works like 5.16”

The runtime shouldhonor that request

Perl should give yousemantics as close aspossible to what you request

New featuresshould not workunder ‘use v5.$older;’

It’s critical that we be able to evolve

We need anescape hatch

We needRule 2

If you declare an old version, you get old syntax and semantics

...at least to thebest of our abilities

Perfection isnot possible

We can get far closer than we do now

Breaking existing code should be a last resort

In limitedcircumstances we will break backward compatibility

Some craziness can’t beﬁxed in an “optional” or lexical way

This is going to be hard work

A lot of hard work

It’s not impossible

Deprecation

1 Our currentdeprecation cycle is 1 year

5.16.0 “It warns in 5.16.0”

5.18.0“It’s gone in 5.18.0”

That’s turning outto be too short

OSVery few operatingsystems release that frequently

Declare by default means we can makesome changes sooner

If it still works in old code, we get to change it with nodeprecation cycle

Some misfeaturesneed to come outlest they block major improvements

If we can’t emulate an old feature for oldcode, we get a longer deprecation cycle

use v5.16 die “It dies in code thatdeclares ‘use v5.16’”

5.16.0 “It warns in older code on 5.16.0”

5.18.0 “It still warns in old code on 5.18.0”

5.20.0“It’s gone in 5.20.0”

2 Rule 2 andOld Modules

We haven’t just beendeprecating and yanking broken old features

We’ve been doing thesame to old modules

CPANThey all end up on CPAN

This hurts users who wrote code with“no non-core deps”

2 Perl 5We need to make iteasier to ship two ﬂavors of Perl 5

(Eagles)Hotel California

Last thing I remember, I wasRunning for the doorI had to find the passage backTo the place I was before’relax,’ said the night man,We are programmed to receive.You can checkout any time you like,But you can never leave!

Perlaka Traditional Perl

(Bob Dylan)The Times,TheyAre A-Changin’

The line it is drawnThe curse it is castThe slow one nowWill later be fastAs the present nowWill later be pastThe order is rapidly fadin’And the first one now will later be lastFor the times they are a-changin’

Perlaka Bootstrappable Perl

There’s work going on to make this easier

PerlPerl is a big language

There are bigger languages

Its harder to manage a big language

It’s harder to learn a big language

It’s harder to ﬁx bugs in a big language

We’re ok, but notamazing at corelanguage dev

Perl As a community, we’re awesome at modules

Perl ?How do we make Perla smaller language?

It’s possible to loadmodules that inject new builtins

It’s possible to loadmodules that inject old builtins

Time to start...

...refactoring

Lots of stuff in perl isnt necessarily part of Perl 5 the language

Perl 5 This stuff is part of Perl 5 the chainsaw

I like our chainsaw

I’m not talking about deprecating this stuff

...just aboutdecoupling it

SysV IPCSysV IPC functions

Socket IOSocket IO functions

Unix / Unix user & group information functions

Unix Unix networkinformation functions

Process and process group functions

Formats

smartmatch

...and probably a bunch of other stuff

use v5.16 5.14If you don’t ‘use v5.16’,you’ll get whatever was in 5.14.

SysV The implementation of SysV might be a module

As a Perl 5 user you won’t need to care

..and shouldn’t be able to tell

In the future we mightﬁx a bug or two in the modularized code

Perl 5 You could take the update without having to upgrade all of Perl 5

Someday we mightremove things from the default runtime

Every feature weexternalize reclaimsprecious memory

Every feature weexternalize reclaims precious sanity

That just means you’ll need to declare youwant an older feature

v5.16...but only if you ask for v5.16

Existing codewon’t break

There are many, many unanswered questions

But it’s doable

Perl Weve been moving pretty fast

We’ve done some things I...

would notdo again

I’m going to be a lotmore skeptical about new features

...at least ones thatdon’t make it easier to have fewer features

We should havesane defaults

Perl 5 There’s lots of crazy in Perl 5

Syntactic Crazy

Semantic Crazy

Internal Crazy

Module Crazy

It may be time toconsider doing away with some of that

We’ve starteddown this road

"use v5.12" "use strict;" “use v5.12” includes “use strict;”

?Where do we go next?

warningswarnings on by default

autodieautodie-esque defaults

return We should throwexceptions rather than just return on failure

I don’t want us to bikeshed anexception hierarchy

Heck, I’d be happy if westarted with dying with well-deﬁned strings

( ) (I’d love an exception hierarchy)

2 open() 2-arg open() gone by default

1 open() 1-arg open() gone by default

No more package separator

Latin-1 Latin-1 autopromote off by default

utf-8utf-8 everything by default

A clean, simplemeta-model with classesand methods

No indirect object syntax by default

"use v5.16"But only if you declare “use v5.16”

Perl Perl needs to be cleaner, simpler and easier to work with

For users...

...and forimplementers

Perl Perl should run everywhere

Not just on everykind of hardware

OS Not just on everyOperating System

VMEvery VM

Every Browser

Every Phone

Perl 5 ?Why isn’t Perl 5 onother runtimes?

“There’s no spec”

RubyThat didn’t stop Ruby

Perl 5 Perl 5 “Only Perl 5 can parse Perl 5”

PPIThat didnt stop PPI

Perl 5 To survive, a desperate hacker needs to be ableto reimplement Perl 5

Thanks!

Super-thanksindividual sponsors!

Questions?http://blog.fsck.comjesse@perl.org@obra

?So, you want to changethe name?

Perl 7 ?To something like Perl 7?

Or Raptor?

Perl 5Our language is called Perl 5

Perl 6 Perl 6 is our precocious kid sister

Perl 5I’m happy to talk about renaming Perl 5...

...if you write me asecond implementation

...that passes the test suite

Perl 5.16 and Beyond - YAPC::Asia 2011

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