use strict;
use warnings;
use Data::Dumper;
use v5.10;

sub f {a=>1,b=>2}

my %result = f(); #converts a a hash passed as an arry
                  #back into a hash

print Dumper \%result;
print "to print just the keys of the hash:\n";
say "$_" for keys %result;

# this is much faster, execution wise...
# passes back a referecne to a hash that has
# been already been created.

sub x
{
   my %result;
   $result{a}=1; #more likely way to set the results
   $result{b}=2;
   return \%result;
}

my $hash_ref = x();
print "to print the keys of this hash\n";
print "$_\n" for keys (%$hash_ref);

print Dumper $hash_ref;

__END__
$VAR1 = {
          'b' => 2,
          'a' => 1
        };
to print just the keys of the hash:
b
a
to print the keys of this hash
a
b
$VAR1 = {
          'a' => 1,
          'b' => 2
        };