Perhaps consider this: Updated code to be perhaps more helpful...
I think an issue here that when you "say", you have to say what you want to "say"! 
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
        };

[download]
PS: I did find that say for keys %{{f}}; did indeed work.
I didn't expect that result, but it does "work".
I find say "$_" for keys %{{f}}; to be easier to understand. However, Perl is gonna make a hash from the return value of f() whether or not you give it name. I prefer the above syntax.

In reply to Re: Using 'keys' on a list by Marshall
in thread Using 'keys' on a list by lammey

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