Calling a function from a rule?

I am missing something about how to properly create a rule.

Thanks to the helpful folks on this list, I am looking a creating some
update able views. So, looks like I need to create a rule and a function
for this. Here is what I am trying as a test.

DROP TRIGGER v_trig_test ON test;

CREATE OR REPLACE FUNCTION v_trig_test() RETURNS trigger AS $$
use 5.010;
use strict;
use warnings;
use Data::Dumper qw(Dumper);

my $new = Dumper $_TD->{new};
my $old = Dumper $_TD->{old};

elog(NOTICE, "old = $old" );
elog(NOTICE, "new = $new" );

return;

$$ LANGUAGE plperlu;

CREATE RULE "_RETURN" AS
ON UPDATE TO purchase_view
DO INSTEAD
SELECT * FROM v_trig_test;

But the select line in the create rule seems to be a syntax error.

Here is my thinking. I have done functions called from triggers, and I am
modeling this after that experience, so I think I need the rule to call the
function, correct?
--
"They that would give up essential liberty for temporary safety deserve
neither liberty nor safety."
-- Benjamin Franklin