returning a cursor from a function?

I have a create function statement that works with Oracle 8i and I'm
trying to create this function in Postgres 8.1.2.

CREATE OR REPLACE FUNCTION pr_user( p0 CHAR ) RETURN
Types.cursor_type IS
rs Types.cursor_type;
BEGIN
OPEN rs FOR
SELECT us.approval_type_code AS us_approval_type_code FROM wbs_users
us WHERE upper( us.username ) = upper( p0 );
return rs;
END;

Could someone lend me a hand here?
Thanks in advance,
-M@