use warnings;
use strict;
use diagnostics; # <------------------------- Important line here.
my $x = "Mmm...donut, thought Homer";
$x =~ /^(Mmm|Yech)\.\.\.(donut|peas)/; # matches
foreach my $expr (1..$#-) 
{
   print "Match $expr: '${$expr}' at position ($-[$expr],$+ [$expr])\n";
}