Perl6 and Parrot

Intro to rewrite of perl¡K why?

New perl6 features

Parrot compiler

WHOI perl software contribution site

perl6 is the next major version of perl

It's a complete rewrite and significant update.

It's a work in progress and won't be available until

probably 2006. But you can follow the progress

and try out new features in beta.

Along with perl6 is the development of Parrot

A new engine that will run perl6 as well as a number of

other interpreters (more later)

Why the rewrite?

perl was getting too large and complex

maintenance was becoming a chore

adding new features was too hard

Goals for perl6

support for new features

may change the way you code, but aren't required

cleaner

faster

easier to use

flexible enough to allow for future changes

Modularize so other languages can use features, like regex engine!

Architectural Considerations

perl6 will still be perl

easy to write to get the job done fast and easily

fundamental syntax is still the same

but a little more consistent

mechanically translatable from perl5

(but will eventually disappear

use perl5ish pragma

#!/usr/bin/perl5

All the good stuff from perl5 will be alive in perl6

New features

exceptions

delegation

continuations

co-routines

currying

Huh??

powerful features that the average user won't use

But prepares perl for the future

Long term usability

want strong, dependable tools with room to grow

Development of perl6 has helped perl5

Latest version is perl5.8 (last stable one was v5.6)

Can expect more releases.

Perl6 will be backward compatible (with switches)

Can now (with v5.8) use some features of perl6 (use perl6ish;)

Other considerations

Perl's parser will be written in perl (perl5!)

using perl's regular expressions

The perl compiler/interpreter systems will be designed so

they can emit C, Java, .NET, C# and other languages

It will run on small devices, like palm.

The system for extending perl with C and C++ will be

replaced with a better, easier system

write C subs that can be called as perl subroutines

Will support more low level programming features,

specify types for variables

bit-wise features for integers and strings

Will also support more high-level programming

functional programming

OOP features

Simple example of some changes in perl6

# PERL5

while ($line = <> ) {

@elt = split(" ", $line);

$elt[0] =~ s/abc/x/;

$count{$elt[1]}++;

}

foreach (sort keys %count) {

print "$_ $count {$_} \n";

}

# same code in PERL6

while ($line = <$ARGS> ) { # diamond operator

@elt = split(" ", $line);

@elt[0] ~~ s/abc/x/; # arrays always use @

%count{ @elt[1] }++; # all hashes use %

}

foreach (sort %count) { # does the right thing

print "$_ %count {$_} \n"; # hash!

}

Other new features¡K

Some operator renaming

-> becomes . (like the rest of the world)

. becomes ~ (stitch)

etc¡K

New operators

// is like || except it tests the left side for definedness

^^ is xor

etc¡K

vector operators

>> << are used to denote "list operations" which work on

all elements of an array or list

(3,8,2,9,3,8) >>-<< 1; # ((2,7,1,8,2,7)

junctive operators

A junctive is a single value that is equivalent to multiple

values

1|2|3 + 4; # 5|6|7

if $roll == 1|2|3 { print "Low roll\n"; }

Chained comparisons

if 3 < $roll <=6 { print "High roll\n" }

Binding

my $y := $x; # both are bound

$y = "hello, world";

print "$x"; # prints hello world

Piping operators

==> and <== are akin to unix pipes

@result = map { $_ * 8}

grep { /^ \d+ $/ }

@data;

@data ==> grep { /^ \d+ $/}

==> map {$_ * 8}

==> @result;

@result <== map {$_ *8}

<== grep { /^ \d+ $/}

<== @data;

zip

interleaves the elements of multiple arrays

for zip (@names,@codes) -> $name,$zipcode {

print "name: $name; Zip code: $zipcode\n";

}

New statements

many new programming features, like try, BEGIN, when, ¡K

for example: given/when is like a case statement, but

much more powerful.

given $val {

when 'A4' { print "2 characters"}

when %B4 { print "hash key $val is defined" }

when /C4/ { die "contains C4!" }

when &D4 { print "returned true"}

}

Can use when without given, since when tests on $_

for (@events) {

when Mouse::Over { change_focus($_) }

when Mouse::Click { make_selection() }

when Window::Close { delete_window() }

when /unknown/ { log_event}$_) }

}

It¡¦s just a nice if-elsif-else construct¡K

Regular expressions

Regular expressions are being extended and will be known

as 'rules'. Gives much more control over pattern matching.

There is a constructor rx that constructs a pattern object

or rule that can be saved for later.

$rule = rx /abc/ ;

A few of the new pattern elements

^ start of string

^^ start of line

$ end of line

$$ end of line

<sp> space

<ws> whitespace (same as \s+)

\n newline

\N not a newline

# Comment. Rules ignore whitespace, must specify

<> Assertion identifiers

<n> match exactly n times

<m..n> match at least m, but no more than m

<m..n>? minimal match m to n times

many others¡K

also regex modifiers to control length of match and number

of matches.

$r = rx :(3) /abc/; # match abc 3 times

Include a predefined rule

$line ~~ /<$rule>/; # =~ is now ~~

Parrot Project

Parrot is strongly related to perl6 but is not perl6

The plan is to separate the interpreter from the parser/compiler

with a virtual machine. Other examples of virtual machines

are JVM and Microsoft¡¦s .NET initiative.

A VM will allow diverse computers all to run the same software.

Perl system execution

Source code <-> parser <-> compiler (to bytecode) <->optimizer <-> runtime

Right now all these routines are embedded in perl. Perl6 will separate them.

Why Parrot? Parrot¡¦s implementation (register based not stack based) is more powerful/faster version than the others.

Speed is paramount concern

Stability is extremely important

Flexibility is also a concern

To see what¡¦s happened with parrot development

www.parrotcode.org

Parrot is much more complete than perl6 since it was needed first before the perl rewrite.

Perl6 will still execute as always¡K Myprog.plx Infiles

All compilation/optimization will happen in background.

Can keep intermediate files, if wanted.

Other languages using parrot

Python, BASIC, forth, Scheme (lisp), Ruby (OO scripting), miniperl,

Cola (Java), Jako (C), even befunge and Ook!

Perl contributed software

Steve Lerner, Chris Hammond and I started up a perl archive site

(also with the help of adam shepard)

Site contains programs and snippets of code to use and study

Anyone can contribute, anyone can use them

(well, must be in whoi.edu domain to get them..)

http://www.whoi.edu/internal/software_contributions

This is the first of many archives that may be implemented

matlab utilities

web utilities

:

Very new so some bugs still need to be worked out. Send problems/comments to

soft-contrib@whoi.edu

This site is not supported (well, very little) nor funded. It was kindly

created from an idea by Steve, Chris and me. More volunteers are welcome!

More contributions are welcome!