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 | Perl 6 | ||
| if ($a = 3 or $a = 4 or $a = 7) {...} | if $a = 3 | 4 | 7 {...} |
| {{if (4 < $a and $a < 12) {...} | if 4 < $a < 12 {...} | ||
| if (4 < $a and $a <= 12) {...} | if $a ~~ 4^..12 {...} |
The err operator eases lot of cases where Perl 5 newbies could fall into traps.
| Perl 5 | Perl 6 |
| $a = defined $b ? $b : $c; | $a = $b // $c; |
Case construct
| Perl 5 | Perl 6 | |
| if ($a = 2 or $a = 5) {...} | given $a { | |
| elseif ($a = 6 or $a = 7 or $a = 8 or $a = 9) {...} | . . when 2 {{ | }} 5 {...} |
| elseif ($a =~ /g/) {...} | . . when 6 .. 9 {...} | |
| else {...} | . . 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 | Perl 6 |
| for my $i (1..15) {...} | for 1..15 -> $i {...} |
| for (my $i=15; $i>1; $i-2) {} | for 1..15:by(-2)- > $i {...} |
| for my $key (keys %hash) { | for %hash.kv -> $key, $value { |
| . . print "$key => $hash{$key}\n"; ... | say "$key => $value"; ... |
| for my $i (0..$#a) { | for zip(@a; @b; @c)- > $a, $b, $c {...} |
| my $a = @a[$i]; | |
| my $b = @b[$i]; | |
| my $c = @c[$i]; | |
| ... |
named parameters in subroutines
| Perl 5 | Perl 6 |
| sub routine { | sub routine ($a, $b, *@rest) {...} |
| . . my $a = shift; | |
| . . my $b = shift; | |
| . . my @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
