Perl6 is a powerful programming language that incorporates many programming paradigms including functional, object-oriented, and reactive programming. It has built-in support for concepts like promises to handle asynchronous code, channels for communicating between asynchronous processes, and sets/bags for storing unique values. The language also has features for rational numbers, lazy evaluation, roles for composition, and easy integration with native libraries. Perl6 aims to provide programmers a flexible toolbox to build applications in many different styles.

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?