###
### chronologically-3
###

## Chapter 3 section 10

@sorted_dates = sort chronologically @dates;

%m2n = 
   ( jan =>  1, feb =>  2, mar =>  3,
     apr =>  4, may =>  5, jun =>  6, 
     jul =>  7, aug =>  8, sep =>  9, 
     oct => 10, nov => 11, dec => 12, );

sub chronologically {
  date_to_string($a) cmp date_to_string($b)
}

sub date_to_string {
  my ($m, $d, $y) = ($_[0] =~ /(\w{3}) (\d+), (\d+)/);
  sprintf "%04d%02d%02d", $y, $m2n{lc $m}, $d;
}