single linked list reverse function

gistfile1.pl

#!/usr/bin/perl

# by Eugen Sobchenko, esobchenko@gmail.com

use strict;
use warnings;

use Data::Dumper;

sub reverse_list {
	my ($previous, $current) = @_;
	my $next = $current->{n};
	$current->{n} = $previous;
	if ($next eq 'null') {
		return $current;
	}
	return reverse_list($current, $next);
}

my $head = { v => 1, n => { v => 2, n => { v => 3, n => 'null' } } };

print "before:\n";
print Dumper( $head );

my $new_head = reverse_list('null', $head);

print "after:\n";
print Dumper( $new_head );