use String::Interpolate qw( );

sub expand {
    my ($rx, $from, $to) = @_;
    if ($from =~ $rx) {
        my $t = String::Interpolate->new();
        $t->($to);
        $t->([ map substr($from, $-[$_], $+[$_] - $-[$_]), 1..$#- ]);
        print "$t\n";
    }
}