use XML::LibXSLT;
use XML::LibXML;

my $xslt = XML::LibXSLT->new();

my $source = XML::LibXML->load_xml(location => 'foo.xml');
my $style_doc = XML::LibXML->load_xml(location=>'bar.xsl', no_cdata=>1);

my $stylesheet = $xslt->parse_stylesheet($style_doc);

my $results = $stylesheet->transform($source);

print $stylesheet->output_as_bytes($results);