Overview - Chapter: 0:Intr, 1:Hist, 2:Design, 3:Var, 4:Op, 5:IO, 6:{}, 7:Sub, 8:OOP, 9:Rx - Appendices: A:Index, B:Tables, C:Best of, D:Delta, E:Links
This is a small tour, showing the best features and improvements of Perl 6 in short examples, compared to similar working Perl 5 examples.
Output
Making output will become simpler and easier for newbies.
| Perl 5(.8) | Perl 6 |
| print "bananas are good\n"; | say "bananas are good"; |
| print "and I said: ".$quotes{"me"}.".\n"; | say "and I said: {%quotes<me>}."; |
File IO
File::Slurp is in the Perl 6 core language and file reading is simpler then ever (and autochomp included).
| Perl 5 | Perl 6 |
| open my $FH, '<', "poetry.txt"; | $content = slurp "poetry.txt"; |
| read $FH, $content, $block_len until eof; | |
| close $FH; | |
| open my $FH, '<', "poetry.txt"; | @content = lines "poetry.txt"; |
| while (<$FH>) { chomp; push @content, $_; } | |
| close $FH; |
Automatic multithreading
Applying operations to junctions and arrays is now syntactically compact and readable. Perl 6 will create threads where appropriate to use multiple processors, cores or hyperthreading for high level language SIMD concurrent processing.
| Perl 5 | Perl 6 |
| my $sum; | my $sum = [+] @numbers; |
| $sum += $_ for @numbers; | |
| for (0 .. $#factor1) { | @product = @factor1 >>*<< @factor2; |
| $product[$] = $factor1[$] * $factor2[$_]; | |
| } |
The Perl 5 code is a simplification, of course Perl6 "does the right thing" when the arrays have different lengths.
Comparsion
Here are junctions, then chained comparison operators.
Perl 5:
if ($a = 3 or $a = 4 or $a = 7) {...}
Perl 6:
if $a = 3|4|7 {...}
Perl 5:
{{if (4 < $a and $a < 12) {...}
Perl 6:
if 4 < $a < 12 {...}
Perl 5:
if (4 < $a and $a <= 12) {...}
Perl 6:
if $a ~~ 4^..12 {...}
The err operator eases lot of cases where Perl 5 newbies could fall into traps.
Perl 5:
$a = defined $b ? $b : $c;
Perl 6:
$a = $b // $c;
Case construct
Perl 5:
if ($a = 2 or $a = 5) {...}
elseif ($a = 6 or $a = 7 or $a = 8 or $a = 9) {...}
elseif ($a =~ /g/) {...}
else {...}
Perl 6:
given $a {when 2 | 5 {...}}
when 6 .. 9 {...}
when 'g' {...}
default {...}
It's clear to read, very versatile and when used in combination with junctions, becomes even clearer.
powerful for loops
Perl 5:
for my $i (1..15) {...}
Perl 6:
for 1..15 -> $i {...}
Perl 5:
for (my $i=15; $i>1; $i-2) {}
Perl 6:
for 1..15:by(-2)- > $i {...}
Perl 5:
for my $key (keys %hash) {print "$key => $hash{$key}\n"; ...
Perl 6:
for %hash.kv -> $key, $value {say "$key => $value"; ...
Perl 5:
for my $i (0..$#a) {my $a = @a[$i];
my $b = @b[$i];
my $c = @c[$i];
...
Perl 6:
for zip(@a; @b; @c)- > $a, $b, $c {...}
named parameters in subroutines
Perl 5:
sub routine {my $a = shift;}
my $b = shift;
my @rest = @_;
Perl 6:
sub routine ($a, $b, *@rest) {...}
Objects with auto generated new and getters and setters
Simple Object creation is now as easy as it gets.
Perl 5:
package Heart::Gold;
sub new {bless {speed => 0 }, shift;}
sub speed {my $self = shift;}
my $speed = shift;
if (defined $speed) { $self->{speed} = $speed }
else { $self->{speed} }
sub stop {my $self = shift;}
$self->{speed} = 0;
Perl 6:
class Heart::Gold {has $.speed;}
method stop { $.speed = 0 }
my Heart::Gold $hg1 .= new;
$hg1.speed = 100;
my $hg2 = $hg1.clone;
$hg2.speed = 50;
The new, getter, setter and clone methods are auto generated. Mthods now are called "method".
Overview - Chapter: 0:Intr, 1:Hist, 2:Design, 3:Var, 4:Op, 5:IO, 6:{}, 7:Sub, 8:OOP, 9:Rx - Appendices: A:Index, B:Tables, C:Best of, D:Delta, E:Links
