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

my @array = qw( a b c );

print "\nSimple join (without parens) - OK\n";
my $cols  = join('],[',@array);
print "cols = $cols\n";

print "\nConcatenation and join (without parens)- NOT OK\n";
$cols  = '[' . join '],[',@array . ']';
print "cols = $cols\n";

print "\nConcatenation and join (with parens) - OK\n";
$cols  = '[' . join('],[',@array) . ']';
print "cols = $cols\n";