#!/usr/bin/perl

use strict;
use warnings;

my @array=("abc","1,2,3","T","pu,pr");
my ($dyn_one,$dyn_two) = @array[1,3];

for my $i ( split /,/, $dyn_one ){
    for my $end ( split /,/, $dyn_two ){
        print sprintf "%s%s%s%s\n", $array[0],$i,$array[2],$end;
    }
}

#!/usr/bin/perl

use strict;
use warnings;

my @array=("abc","1,2,3","T","pu,pr");
my @strings = (shift @array);

for my $i ( @array ){
    if( index($i, ',') != -1 ){
        @strings = map{my $j = $_; map{ $_ . $j }@strings}split /,/, $i;
    }
    else{
        $_ .= $i for @strings;
    }
}

print $_,"\n" for @strings;