use constant EOL_CHAR => "\n";

my @arr = qw( 123 456 789 );  # like bash and IFS

$\ = EOL_CHAR;

foreach(@arr) {
  
  print $_;
}

use constant EOL_CHAR => "End";
print EOL_CHAR;

Constant subroutine main::EOL_CHAR redefined at /usr/lib/perl5/5.8.0/constant.pm line 108.
123
456
789
End