SQL stored function inserting and returning data in a row.

Hi,

Is there any way to define a SQL stored function that inserts a row in a
table and returns the serial generated?

CREATE TABLE matchmaking_session
(
session_id bigint NOT NULL DEFAULT
nextval('seq_matchmaking_session_id'),
...
);

CREATE FUNCTION create_matchmaking_sesssion(...)
RETURNS bigint
AS $$
INSERT INTO matchmaking_session(...)
VALUES (...)
RETURNING session_id;
$$ LANGUAGE SQL;

2008-01-10 22:08:48 EST ERROR: return type mismatch in function
declared to return bigint
2008-01-10 22:08:48 EST DETAIL: Function's final statement must be a
SELECT.
2008-01-10 22:08:48 EST CONTEXT: SQL function
"create_matchmaking_sesssion"

I can easily convert this code into a PL/pgSQL function, but I'm
thinking that pure SQL is more natural (and faster?) for such a stored
function.

Regards,

--
Daniel