#!/usr/bin/perl
use strict;
use Data::Dumper::Simple;

my %a = (
    one => 'red',
    two => '',
    three => 'blue'
);

my @rtn = map {$a{$_} !~ /^$/;} keys(%a);
print Dumper(@rtn);
print "Keys w/ non-empty values: " . scalar(@rtn) . "\n";

__RESULTS__
@rtn = (
         1,
         1,
         ''
       );
Keys w/ non-empty values: 3