"Perl 6 Operators"

Speaker: Juerd
Duration: 45 minutes
Level: Advanced

Het Nederlandse origineel is hier.

Introduction

• Expressive strength is in operators
• »~&=«

Summary

• Some things change
• A lot is added
• More line noise + more ease
  == more Perl

Perl 5 operators

-> ++ -- ** ! ~ \ and u+ u- =~ !~ * / % x + - . << >> < > <= >= lt gt le ge == != <=> eq ne cmp & | ^ && || .. ... ?: = op= , => not and or xor

Operators that stay the same

! != % && * ** + ++ - -- .. / < <= <=> == > >= \ and and cmp eq ge gt le lt ne not op= or xor ||

Changing operators

-> . ~ ^ ?: x => & | ^ << >>

New operators

<> «» »« | & ^ := ::= =:= ^^ // ? + ~ true err ¥ : ...

The big shift

• -> becomes .
• . becomes ~
• ~ becomes ^
• ^ becomes +^, ~^ or ?^

More changes

• ?: becomes ??::
• x becomes x and xx
• => will construct pairs

Bitwise ops

	&	|	^	<	>
+	+&	+|	+^	+<	+>	numeric
~	~&	~|	~^	~<	~>	stringy
?	?&	?|	?^			boolean

Linenoise explained

(»~&=«)

$foo ~&= " "
is just
$foo = $foo ~& " "

»« explained later on

Smart matching

• =~ goes away
• ~~ does a smart match
• !~ does too, but negated
• compare anything to anything

Examples with ~~

if $string ~~ $regex { ... }
if @array  ~~ $element { ... }    # grep
if $string ~~ $substring { ... }  # eq
if $class  ~~ SuperClass { ... }  # isa

Filler

• and has &&
• or has ||
• xor gets ^^

Defined-or

my $foo = $input || 'default';
my $foo = $input // 'default';

err is the low precedence version

Word lists

• < foo bar baz > is the new qw
• « foo $bar baz » interpolates

Pairs

• foo => "bar"
• :foo("bar")
• :foo<bar>
• :foo«bar»

:foo means :foo(1)

Hash subscripts

• %hash{foo} is %hash{ foo() }
• %hash<foo> is %hash{ 'foo' }

Binding

• $bar := $foo
• $bar ::= $foo
• $foo =:= $bar
  (p5: \$foo == \$bar)

Forcing context

• + numeric
• ~ string
• ? boolean, with low prec. true
• (! boolean, with low prec. not)

Zipping

¥ or Y or zip()

@foo ¥ @bar
# is actually
@foo[0], @bar[0],
@foo[1], @bar[1],
@foo[2], @bar[2], ...

Hyper

@quux = map { $_ + 3 } @foo
@quux = @foo »+ 3;

@quux = map { @foo[$_] + @bar[$_] }
    0 .. min(@foo.last, @bar.last);
@quux = @foo »+« @bar;

Line noise explained

@ips »~&=« @netmasks

Junctions!!!

if $foo == 'foo' | 'bar' { ... }
if $foo & $bar > 3 { ... }

Kinds of junctions

• |, any()
• &, all()
• ^, none()
• one() is any() with a limitation

Ease

if  $a != $c
and $a != $d 
and $b != $c 
and $b != $d { ... }

becomes

if $a & $b == $c ^ $d { ... }

More ease

if  $a != $d and $a != $e and $a != $f
and $b != $d and $b != $e and $b != $f
and $c != $d and $c != $e and $c != $f { ... }

becomes

if all($a, $b, $c)
== none($d, $e, $f) { ... }

Real power

if all(@foo) != none(@bar)
    { ... }

Junctions as normal values

my $junc = 11 | 20;

$junc += 5;
# $junc is now 16 | 25

$j2 = sqrt($junc);
# $j2 is now 4 | 5

Not explained

• -> ("pointy sub")
• * ("splat")
• ** ("steam roller")
• <== and ==> ("pipes")

Books

• Perl 6 and Parrot Essentials, 2nd ed.
  By Allison Randal, Dan Sugalski, Leopold Tötsch
  ISBN: 059600737X
• Perl 6 Now: Core Ideas Illustrated With Perl 5
  By Scott Walters
  ISBN: 1590593952

The end