use warnings;
use strict;
use Data::Dumper;

namedMunge(p1=>'aValU', foo=>undef);
sub namedMunge
{
	my %ParamHash = @_;
	my %defaults = ( foo=>0, bar=>42, baz=>'pie');
	ApplyDefaultParams(\%ParamHash, \%defaults);
	
	# Do Munge here!
	
	print Dumper \%ParamHash;
}

sub ApplyDefaultParams
{
	my $ParamHashRef = shift;
	my $DefaultsHashRef = shift;
	
	foreach my $key (keys(%$DefaultsHashRef))
	{
		if (not exists($ParamHashRef->{$key}))
		{
			$ParamHashRef->{$key} = $DefaultsHashRef->{$key};
		}
	}
	return $ParamHashRef;
}

##</code><code>##

$VAR1 = {
          'foo' => undef,
          'baz' => 'pie',
          'p1' => 'aValU',
          'bar' => 42
        };