Ten Things You Need To Know about Perl 6
Jeffrey Goff, Evozon Systems LLC
OSCON London 2016
https://github.com/drforr
http://theperlfisher.blogspot.ro
资源
perl6.org (obviously)
docs.perl6.org – Online documentation
modules.perl6.org – CPAN Lite
rakudo.org – Where to get the latest
https://github.com/tadzik/rakudobrew – Perlbrew for Perl 6
https://github.com/tadzik/panda/ – Module installer
irc://irc.freenode.org/perl6 – #perl6 on IRC.freenode.org
http://rosettacode.org/wiki/Category:Perl_6 – Sample source
要闻
- 干净, 一次性的可解析的文法
- 对用户友好的错误信息
- 友好的 Unicode
- 对初学者有帮助的符号
- Math that works
- 函数签名
- 用正则表达式引导
- OO with a type lattice built on a Metaprogramming model
- 自定义运算符
- 内置并发
一次性文法
my @doctor = { :first('Christopher'), :last('Eccleston'), years => 1 },
{ :first('David'), :last('Tennant'), years => 4 },
{ :first('Matt'), :last('Smith'), years => 4 },
{ :first('Peter'), :last('Capaldi'), years => 3 };
say 'First New Who Doctor: ', @doctor[0]{'first'}, ' ', @doctor[0]<last>;
say "Average run: " ~ @doctor.elems R/ sum map { .<years> }, @doctor;
R/ 运算符会对调两边的表达式再进行计算。
my %hash := { :name('Larry Wall'), :sex('male') }; # {name => Larry Wall, sex => male}
say %hash{'name'}; # Larry Wall
say %hash.<name>; # Larry Wall
访问散列的键值的另外一种语法是 %hash.<key>, 尖括号自动为 key 添加引号。
错误信息
sub mean( @a ) {
my $sum = sum( @a )
( $sum / @a.elems )
}
say mean 1, 2, 4;
$ perl6 test.pl6
Two terms in a row across lines (missing semicolon or comma?)
at /home/jgoff/test.pl6:2
------> my $sum = sum( @a )⏏<EOL>
expecting any of:
infix
infix stopper
postfix
statement end
statement modifier
statement modifier loop
Unicode Friendly
my $α = 2 + ⅒ ;
say $α ÷ 2;
# 1.05
Or, really old-school
use Slang::Roman;
say 0rↀ + 0rDCLXVI;
# 1666
my $a = 0rIV / 0rM;
say $a;
# 0.004
This is really just a teaser to show off how powerful the internals really are.
The module itself is a bit too complex to show, but I like to think that the
fact that I can go in and muck about with the actual grammar, changing how
numbers are read and stored internally speaks volumes.
有意义的符号
my @powers = 1, 2, 4, 8;
my %foo = :name('Jeff'), :division('Programming');
say @powers[ 1, 2 ];
say %foo<name>;
# (2 4)
# Jeff
浮点数
$ perl -E 'say 0.1 + 0.2 - 0.3'
+5.55111512312578e-17
+$ ruby -e 'print 0.1 + 0.2 - 0.3'
+5.55111512312578e-17
+$ python -c 'print 0.1 + 0.2 - 0.3'
+5.55111512312578e-17
+$ perl6 -e 'say 0.1 + 0.2 - 0.3'
+0
+$ perl6 -e'say (0.1).nude'
+(1 10)
函数签名
sub plus( Int $a, Int $b ) {
$a + $b
}
say plus 1, 2;
# 3
say plus 1, 2, 3;
===SORRY!=== Error while compiling -e
Calling a(Int, Int, Int) will never work with declared signature
(Int $a, Int $b)
at -e:1
------> ub foo( Int $a, Int $b ) { $a + $b }; say ⏏foo 1, 2, 3;
不那么正规的表达式
my $id = '[ { "first": "Christopher", "last": "Eccleston", "id": 1 } ]';
my regex Str { '"' (<-[ " ]>+) '"' };
my regex Integer { \d+ };
my regex Value { <Integer> | <Str> };
my regex Pair { <Str> ':' \s+ <Value> };
my regex Pairs { '{' \s+ <Pair>+ %% (',' \s+) \s+ '}' };
my regex List { '[' \s+ <Pairs>+ %% (',' \s+) \s+ ']' };
$id ~~ m{ <List> };
say $/;
面向对象
enum Chirality <left right>;
enum Effort <minimum average maximum>;
class Hand {
has Chirality $.chirality;
has $.content;
}
role Humanoid {
has Hand $.left-hand .= new( :chirality( left ) );
has Hand $.right-hand .= new( :chirality( right ) );
}
class Character does Humanoid {
has Str $.name is required;
has Int @.Attr where 0 < * <= 18;
method attack( Character $enemy, Effort $effort ) { ... }
}
class Sword { has Int $.Dmg }
my $Wade = Character.new(:name('Wade'));
$Wade.left-hand.content = Sword.new( Dmg => 5 );
$Wade.right-hand.content = Sword.new( Dmg => 5 );
my $Francis = Character.new(:name('Francis'));
$Wade.attack($Francis,maximum);
看呐,合适的列表!
my $fh = open 'sample.tsv', :r;
my @line;
for $fh.lines -> $line {
my ( $id, $last-name, $first-name ) =
$line.chomp.split( "\t" );
@line[$id - 1] = $last-name, $first-name;
}
close $fh;
say @line;
# [("Tyler", "Rose"), ("Smith", "Mickey"),
("Jones", "Martha"), ("Noble", "Donna")]
自定义运算符
multi sub prefix:<∑>( *@values ) {
[+] @values
}
my $total = ∑ 0 ... ∞;
multi sub postfix:<⁺>( $x ) { $x.charge( +1 ) }
multi sub postfix:<⁻>( $x ) { $x.charge( -1 ) }
multi sub prefix:<√>( $x ) { sqrt( $x ) }
W⁺ = (-W¹ + iW²)/√2 ;
W⁻ = (-W¹ + iW²)/√2 ;
Perl 6 风格
for 'sample.txt'.IO.lines.kv -> $index, $line {
my ( $method, $id, $name, timestamp ) = $line.chomp.split( "\t" );
given $method {
when 'create' { %object{$id} = $name, $timestamp }
when 'delete' { %object{$id}:delete }
}
if $method eq 'read' | 'update' | 'delete' {
say "missing object on line $index" unless %object{$id}
}
}
