my $str = 'convert perl-to python';
my $bits =()= $str =~ /[ -]/g;

for (0 .. (1<<$bits)-1) {
    my @l = split//,unpack'b*',pack'C,',$_;
    (my $out = $str) =~ s/[ -]/(' ','-')[shift @l]/ge;
    print $out, $/;
}
__END__
convert perl to python
convert-perl to python
convert perl-to python
convert-perl-to python
convert perl to-python
convert-perl to-python
convert perl-to-python
convert-perl-to-python