You could look at the any() function from the List::MoreUtils module. I think it would be something like so:

#!/usr/bin/perl -w
use strict;
use List::MoreUtils qw(any);

my @typedefs = qw(do re me fa so la ti do);
while ( my $line = <DATA> ) {
    if ( any { $line =~ /$_/ } @typedefs ) {
        # perform various actions here if line match
        print $line;
    }
}

exit 0;

__END__
do
me
a
favour
will
you
[download]

This prints:

do
me
favour
[download]

UPDATE

From the docs:

Using the functions from this module however should give slightly better performance as everything is implemented in C.

Hope that helps =)