perl

Implementation of programming language Perl

Standard implementation of Perl, written in C.

Examples:

Hello, World!:

Example for versions perl 5.8.8 
#!/usr/bin/env perl
print "Hello, world!\n";

Factorial:

Example for versions perl 5.8.8

This example uses the reduce function from the List::Util module. Note that we have to put an extra 1 in the beginning, so that it will work when 1 .. $n is empty (i.e. when $n is 0). 

use List::Util qw(reduce);
sub fact {
  my $n = shift;
  reduce { $a * $b } 1, 1 .. $n
}

foreach my $i (1..16) {
    print "$i! = ", fact($i), "\n";
}

Factorial:

Example for versions perl 5.8.8 
sub fact {
  my $n = shift;
  $n == 0 ? 1 : $n*fact($n-1);
}

foreach my $i (1..16) {
    print "$i! = ", fact($i), "\n";
}

Factorial:

Example for versions perl 5.8.8 
sub fact {
  my $n = shift;
  my $result = 1;
  foreach my $i (1 .. $n) {
    $result *= $i;
  }
  $result
}

foreach my $i (1..16) {
    print "$i! = ", fact($i), "\n";
}

Fibonacci numbers:

Example for versions perl 5.8.8

naive recursive solution 

sub fibonacci {
  my $n = shift;
  $n < 3 ? 1 : fibonacci($n-1) + fibonacci($n-2)
}

foreach (1..16) {
  print fibonacci($_), "\n";
}

Fibonacci numbers:

Example for versions Perl 6 (alpha)

Not the shortest possible implementation, but perhaps the easiest to read and understand. 

sub fib { 1,1...{$^x + $^y} }

fib[^16], '...' ==> join(', ') ==> say;

Factorial:

Example for versions Perl 6 (alpha)

This version uses the reduction metaoperator to multiply every number from 1 to N (the leading [*] means “apply the * operator between each element of the following list”).

Note that the say statement could also be written as: 

say "$i! = &fact($i)";

with the function call interpolated directly into the string being printed. 

sub fact($n) { [*] 1..$n }

for 1..16 -> $i {
    say "$i! = ", fact($i);
}

Hello, World!:

Example for versions Perl 6 (alpha)

The comma at the end is optional.

This is also a valid Perl 5.10 program. 

say 'Hello, World!';