use Math::BooleanEval;
my $bool = Math::BooleanEval->new('yes|no');

# evaluate each defined item in the expression to 1 or 0
foreach my $item (@{$bool->{'arr'}}){
    next unless defined $item;
    $item = ($item =~ m/^no|off|false|null$/i) ? 0 : 1;
}

# evaluate the expression
print $bool->eval();