Perl6 is a powerful programming language that incorporates many programming paradigms including functional, object oriented, reactive, and event based programming. It aims to provide programmers with a toolbox of features to build applications in many different styles. The language includes features like junctions, promises, channels, supplies, sets, roles, and strong support for Unicode. It also allows calling external native libraries and has built-in support for rational numbers, sequences, and lazy evaluation. Perl6 code examples are provided to demonstrate various features like List utilities, junctions, promises, channels/supplies, roles, and native calls. Further reading resources are also referenced.

1. Perl6
A Whistle Stop Tour

2. Obligatory About Me Slide
Hi.
I’m Simon. (Also known as Scimon in many places)
I write Perl and when I can Perl6.
I’ve been doing it for 15 years and a bit. (Not the Perl6… well)
Now working at Zoopla. We’re hiring, (not sure where we’ll put you…)
Wrote Timer::Breakable, writing more modules.

3. A Disclaimer
I am still learning Perl6.
It’s a massive powerful language with a lot of scope to create amazing stuff.
Some of the things I say today may be wrong.
This will be because I still don’t fully understand some of the really neat things I’m
playing with.
But all the code examples I give work!
I tested them all.

4. Humourous Caption Slide
The Year of Linux on the Desktop!
1998, 1999, 2000, 2001, 2002 …
The Year of Perl6 in Production ?
2018...

5. Multiple Programming Paradigms
What’s your poison?
● Functional Programming ?
● Object Orientated ?
● Reactive or Event Based ?
● Strongly Typed ?
● Weakly Typed ?
Perl6 builds in the concept of the swiss army chainsaw and gives you a toolbox
from which you can build whatever chainsaw you want.

6. List::Util
● reduce : [+] @a or @a.reduce(*+*)
● any : so any(@a) > 10
● all : so all(@a) > 10
● none : so none(@a) > 10
● first : @a.first( * > 10 )
● max : @a.max
● maxstr : @a.max( *.Str )
● min : @a.min
● minstr : @a.min( *.Str )
● product : [*] @a or @a.reduce(* * *)
● sum : @a ?? @a.sum !! Nil
● sum0 : @a.sum
● shuffle : @a.pick(@a)
● uniq : @a.unique
● uniqnum : @a.unique( :as( *.Num ) )
● uniqstr : @a.unique( :as( *.Str ) )
Perl6 has Pairs as a Type making the pair methods redundant.
Note that Perl6 is typed and casting a string to a number may raise an exception.

7. Junctions
my @array = ( False, False, False );
my ( $all, $none, $any ) = ( all(@array), none(@array), any(@array) );
say "All : {$all.so} None: {$none.so} Any: {$any.so}";
All: False None: True Any: False
@array[0] = True;
say "All : {$all.so} None: {$none.so} Any: {$any.so}";
All: False None: False Any: True
4 < 1^2^3^4^5 < 2 == True; # one(1,2,3,4,5)
4 < 1|2|3|4|5 < 2 == True; # any(1,2,3,4,5)
4 < 1&2&3&4&5 < 2 == False; # all(1,2,3,4,5)

8. Junction Sudoku
my @cells =
[ [ 2, 1, 3, 4 ],
[ 3, 4, 1, 2 ],
[ 2, 3, 4, 1 ],
[ 4, 1, 2, 3 ] ];
my @test-array;
for 0..3 -> $c {
@test-array.push(
one(
(0..3).map(
{
@cells[$c][$_]
}
)
)
);
}

9. Junction Sudoku
my @cells =
[ [ 2, 1, 3, 4 ],
[ 3, 4, 1, 2 ],
[ 2, 3, 4, 1 ],
[ 4, 1, 2, 3 ] ];
my @test-array;
for 0..3 -> $c {
@test-array.push(
one(
(0..3).map(
{
@cells[$_][$c]
}
)
)
);
}

10. Junction Sudoku
my @cells =
[ [ 2, 1, 3, 4 ],
[ 3, 4, 1, 2 ],
[ 2, 3, 4, 1 ],
[ 4, 1, 2, 3 ] ];
my @test-array;
for (0,0), (0,2),
(2,0), (2,2) -> ($y, $x) {
@test-array.push(
one(
@cells[$y][$x],
@cells[$y][$x+1],
@cells[$y+1][$x],
@cells[$y+1][$x+1]
)
);
}

11. Junction Sudoku
my @cells =
[ [ 2, 1, 3, 4 ],
[ 3, 4, 1, 2 ],
[ 2, 3, 4, 1 ],
[ 4, 1, 2, 3 ] ];
{ … Setup Here … }
my $test-all = all( @test-array );
sub test {
? [&&] (1..4).map( * == $test-all );
}

12. Junction Sudoku (Complete)
my @cells = [ [ 2, 1, 3, 4 ],
[ 3, 4, 1, 2 ],
[ 2, 3, 4, 1 ],
[ 4, 1, 2, 3 ] ];
my @test-array;
for (0,0), (0,2), (2,0), (2,2) -> ($y, $x) {
@test-array.push(
one( @cells[$y][$x], @cells[$y][$x+1],
@cells[$y+1][$x], @cells[$y+1][$x+1] ) );
}
for 0..3 -> $c {
@test-array.push(
one( (0..3).map( { @cells[$c][$_] } ) ) );
@test-array.push(
one( (0..3).map( { @cells[$_][$c] } ) ) );
}
my $test-all = all( @test-array );
sub test {
so [&&] (1..4).map( * == $test-all );
}
sub output {
@cells.map( *.join( " " ) ).join( "n" ).say;
}
output();
say test() ?? "Valid" !! "Invalid";
( @cells[0][0], @cells[0][1] ) =
( @cells[0][1], @cells[0][0] );
output();
say test() ?? "Valid" !! "Invalid";

13. Promises
“Asynchronous programming for mortals” or “No more callback hell”
my $p1 = start { sleep 3; print “Or a simple start? ”; };
my $p2 = Promise.in(2).then( { print “Why not use a timer? ” } );
my $p3 = Promise.anyof( $p1, $p2 ).then( { print “Something is done. ” } );
my $p4 = Promise.allof( $p1, $p2, $p3 ).then( { print “All the promises done.” } );
print “Promises Begun… ”;
await( $p1, $p2, $p3, $p4 );
say “All done.”;
Promises Begun… Why not use a timer? Something is done. Or a simple start? All the
promises done. All done.
With some pauses…

14. Channels and Supplies
constant children = 8;
sub MAIN( Str $text ) {
my $dir-channel = Channel.new();
my $file-channel = Channel.new();
my @readers;
for (^8) -> $idx {
@readers[$idx] = Promise.new();
my $sup = $file-channel.Supply.map( -> $path {
my @a = $path.lines.grep( {
defined $_.index($text)
} ); $path => @a
} ).tap( -> $data {
for $data.value { say("{$data.key} : {$_}") }
}, done => { @readers[$idx].keep } );
}
for dir( "." ) -> $p { $dir-channel.send($p) };
loop {
if $dir-channel.poll -> $path {
if ( $path.d ) {
$dir-channel.send( $_ )
for dir( $path )
} elsif ( $path.f ) {
$file-channel.send( $path );
}
} else {
$dir-channel.close;
$file-channel.close;
last;
}
}
await( @readers );
}

15. Channels and Supplies (Feeds : Secret Sauce)
my $sup = $file-channel.Supply
.map( -> $path {
my @a = $path.lines.grep( {
defined $_.index($text)
} ); $path => @a
} )
.tap( -> $data {
for $data.value { say("{$data.key} : {$_}") }
}, done => { @readers[$idx].keep } );

16. Sequences, Lazy Evaluation and Rational Numbers
my @primes = (1..*).grep( *.is-prime );
my @evens = 2,4,6...*;
my @fib = 1, 1, * + * ... *;
my $div0 = 42 / 0;
say $div0.nude; # NU(merator and) DE(nominator)
(42 0)
say 0.2 + 0.1 - 0.3 == 0; True

17. Sets and Bags
my @primes = (1..*).grep( *.is-prime );
my @fib = 1,2,*+*...*;
my $prime-set = set( @primes[0..50] );
say $_, " prime? ", $_ ∈ $prime-set
for @fib[0..5];
say $prime-set ∩ @fib[0..10];
(elem) and ∈ are synonyms as are (&) and ∩
Note : Set operators auto coerce their args to
Sets.
1 prime? False
2 prime? True
3 prime? True
5 prime? True
8 prime? False
13 prime? True
set(13 2 3 5 89)

18. Native Call
use Cairo;
given Cairo::Image.create(Cairo::FORMAT_ARGB32, 128, 128) {
given Cairo::Context.new($_) {
for 1..16 -> $x {
for 1..16 -> $y {
.rgb($x/16, $y/16, 0 );
.rectangle( 8 * ( $x - 1), 8 * ( $y - 1 ), 8 , 8 );
.fill;
}
}
};
.write_png("test2.png")
}
https://github.com/timo/cairo-p6

19. NativeCall (A peek inside)
method write_to_png(Str $filename)
returns int32
is native($cairolib)
is symbol('cairo_surface_write_to_png') {*}
method rectangle(num64 $x, num64 $y, num64 $w, num64 $h)
is native($cairolib)
is symbol('cairo_rectangle') {*}
That simple. Here $cairolib is either 'libcairo-2' or ('cairo', v2)
depending on the architecture.

20. Roles
Yeah you know roles right? Well what about this?
role logger {
method log-msg ( Str $msg ) { say “{$msg} : {self.perl}” }
};
my $num = 5;
$num.?log-msg( "Not a logger" );
$num does logger;
$num.?log-msg( "Loggable" );
Or
my $result = 0 but True;

21. Unicode
my $á1 = “c[LATIN SMALL LETTER A WITH ACUTE]”; # Smart Quotes!
my $á2 = “ax301”;
say “$á1 : $á2”;
á : á
say $á1 eq á2;
True
say “$á1 : $á2”.uc;
Á : Á
my $æ = 2;
$æ = ( $æ * ¾ )²;
say “æ => $æ”;
æ => 2.25

22. All the other stuff
● Grammars
● Imaginary Numbers
● Proper Exceptions
● CPAN
● Meta Objects
● Telemetry
● JVM
● RakudoJS
● IO::Notification
● Date and DateTime built in
● (And so much more)

23. Further Reading (and Viewing)
● Perl 6 Docs - https://docs.perl6.org/
● High End Unicode in Perl 6 - https://youtu.be/Oj_lgf7A2LM
● Perl6 Superglue for the 21st Century - https://www.youtube.com/watch?v=q8stPrG1rDo
● Think Perl 6 - http://greenteapress.com/wp/think-perl-6/
● Using Perl 6 - https://deeptext.media/using-perl6
● Learning Perl 6 (On the Way) - https://www.learningperl6.com/
● Cro - http://cro.services/
● Bailador - https://github.com/Bailador/Bailador
● Sparrowdo - https://github.com/melezhik/sparrowdo
● Spitsh - https://github.com/spitsh/spitsh
● Roles vs Inheritance - https://www.youtube.com/watch?v=cjoWu4eq1Tw

24. Questions?