my $mathadd = Date::Math::Add->new();
my $mathdst = Date::Math::DaylightSavingsTime->new();
my $mathweekday = Date::Math::WeekdayCalculations->new();

print $mathadd->addition("2016/05/16", 5, "days");

if($mathdst->daylightsavingstime_in_effect) {
    print "DST is in effect.";
}

print "That falls on a ", $mathweekday->weekday_name($mathadd->addition("2016/05/16", 5, "days"));