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