wordA wordB wordC
wordD wordA wordE wordF

##</code><code>##

my $pos_file = '/path/to/positive.txt';
my $neg_file = '/path/to/negative.txt';

my $categorizer = Algorithm::NaiveBayes->new;
my $fh;

open($fh,"<",$pos_file) or die "Could not open $pos_file: $!";
while (my $sentence = <$fh>) {
	chomp $sentence;
	my @words = split(' ',$sentence);
	my %positive;
	$positive{$_}++ for @words;
	$categorizer->add_instance(
		attributes => \%positive,
		label => 'positive');
}
close($fh);

open($fh,"<",$neg_file) or die "Could not open $neg_file: $!";
while (my $sentence = <$fh>) {
	chomp $sentence;
	my @words = split(' ',$sentence);
	my %negative;
	$negative{$_}++ for @words;
	$categorizer->add_instance(
		attributes => \%negative,
		label => 'negative');
}
close($fh);

$categorizer->train;

##</code><code>##

my $sentence_file = '/path/to/sentence.txt';

open($fh,"<",$sentence_file) or die "Could not open $sentence_file: $!";
while (my $sentence = <$fh>) {
	chomp $sentence;
	my @words = split(' ',$sentence);
	my %test;
	$test{$_}++ for @words;
	my $probability = $categorizer->predict(attributes => \%test);
	# ...
	# do what you need with $probability
}
close($fh);