plpgsql returning array

Hello,
in Postgresql, I have a function like this

CREATE OR REPLACE FUNCTION foo()
RETURNS text[] AS
$BODY$
declare
a text;
b text;
arr text[];
begin
a = 'a';
b = 'b';
arr[0] = a;
arr[1] = b;
return arr;
end;
$BODY$
LANGUAGE 'plpgsql' VOLATILE;

In PHP I would like to read my returned arr.
<?php
$message = pg_fetch_result(pg_query("select foo()"),0,0);
print_r($message);
?>
prints something like:
[0:1]={a,b}

I could parse that results, as a string but I'd rather have a nice array. Any idea how I should change the function and/or the php codes?
Thanks in advance
Jean