#!/usr/bin/perl -ln

use strict;
use warnings;

sub expand;
sub doit;

print for expand $_;

sub expand {
    doit split /\[(.*?)\]/, shift, -1;
}

sub doit {
    return @_ if @_ == 1;
    my ($pre,$pat,$post)=splice @_, 0, 3;
    map { doit $pre . $_ . $post, @_ }
      map { /(\w+):(\w+)/ ? $1..$2 : $_ }
      split /,/, $pat;
    }

__END__