>>97
use Time::Piece;
use Time::Seconds;
my $t = Time::Piece->strptime("2011-06-01","%Y-%m-%d");
say ($t - ONE_DAY); # Tue May 31 00:00:00 2011
say ($t - ONE_WEEK); # Wed May 25 00:00:00 2011

>>98
Date::Simple もたしかにいいね