Hi reswaran,

I'm assuming you meant push @comb, [$val, @$_] for combine \@rest, $n-1; (please use <code> tags).

I'm not sure what combine is, but I'm going to guess that it's a function that returns a list of array references (to find out more, find out which module combine is coming from and read its documentation). For testing, I'm going to substitute the function call with a plain array.

Then, for will loop over the elements of the list returned by combine and set $_ to each of those values. [ ... ] creates a new array reference. This new arrayref will contain the value $val, followed by the elements of the arrayref which is stored in $_ and dereferenced via @$_.

Here, I've rewritten the for loop in a more verbose but hopefully more clear way:

use warnings;
use strict;

my $val = "foo";
my @combine = (["bar","quz"],["abc","def"]);

my @comb;
for my $el (@combine) {
    push @comb, [$val, @$el];
}

use Data::Dumper;
print Dumper(\@comb);

__END__
$VAR1 = [
          [ 'foo', 'bar', 'quz' ],
          [ 'foo', 'abc', 'def' ]
        ];
[download]

Hope this helps,
-- Hauke D