use re 'debug';

for my $i (1..2) {
   for my $re (qw( abc def )) {
      $i =~ /$re/;
   }
}

##</code><code>##

Compiling REx `abc'         <------------
size 3 first at 1
   1: EXACT <abc>(3)
   3: END(0)
anchored `abc' at 0 (checking anchored isall) minlen 3 
Freeing REx: `abc'
Compiling REx `def'         <------------
size 3 first at 1
   1: EXACT <def>(3)
   3: END(0)
anchored `def' at 0 (checking anchored isall) minlen 3 
Freeing REx: `def'
Compiling REx `abc'         <------------
size 3 first at 1
   1: EXACT <abc>(3)
   3: END(0)
anchored `abc' at 0 (checking anchored isall) minlen 3 
Freeing REx: `abc'
Compiling REx `def'         <------------
size 3 first at 1
   1: EXACT <def>(3)
   3: END(0)
anchored `def' at 0 (checking anchored isall) minlen 3 
Freeing REx: `def'

##</code><code>##

use re 'debug';

for my $re (qw( abc def )) {
   for my $i (1..2) {
      $i =~ /$re/;
   }
}

##</code><code>##

Compiling REx `abc'         <------------
size 3 first at 1
   1: EXACT <abc>(3)
   3: END(0)
anchored `abc' at 0 (checking anchored isall) minlen 3 
Freeing REx: `abc'
Compiling REx `def'         <------------
size 3 first at 1
   1: EXACT <def>(3)
   3: END(0)
anchored `def' at 0 (checking anchored isall) minlen 3 
Freeing REx: `def'