#!/usr/bin/perl
use strict;
use warnings;

# works as expected
my $text = 'Hello world';
$text=~ s/(\w+)/$1 Perl/;
print "Regular regex: $text\n";

# but now try with variable interpolation
my $text2 = 'Hello world';
my $match = qr/(\w+)/;
my $replace = '$1 Perl';

$text2 =~ s/$match/$replace/e;

# not what I want
print "Interpolated regex: $text2\n";