o gatilho não pode acessar o loop da coluna

SSCCE: O seguinte script:

$ cat test.sql 
CREATE TABLE public.foo (
loop INTEGER
);

CREATE OR REPLACE FUNCTION public.foo_fun(loop INTEGER) RETURNS BOOLEAN AS $$
    SELECT TRUE;
$$ LANGUAGE SQL;

CREATE OR REPLACE FUNCTION public.foo_tr_fun() RETURNS TRIGGER AS $$
DECLARE
    fRV BOOLEAN;
BEGIN
    SELECT public.foo_fun(NEW.loop) INTO fRV;
IF fRV THEN
    RETURN NEW;
ELSE
    RAISE EXCEPTION 'bar';
END IF;
END
$$ LANGUAGE plpgsql;

CREATE TRIGGER foo_tr AFTER INSERT OR UPDATE ON public.foo
FOR EACH ROW
EXECUTE PROCEDURE public.foo_tr_fun();

... com o qual corro:

psql -v ON_ERROR_STOP=1 --quiet -X -U some-user -d some-db -f test.sql

... quando tento inserir uma linha em foo(de psql):

$ psql -U some-user some-db
psql (9.1.14)
Type "help" for help.

RegTAP=> SELECT * FROM public.foo;
 loop 
------
(0 rows)

RegTAP=> INSERT INTO public.foo(loop) VALUES(0);
ERROR:  record "new" has no field "loop"
LINE 1: SELECT public.foo_fun(NEW.loop)
                              ^
QUERY:  SELECT public.foo_fun(NEW.loop)
CONTEXT:  PL/pgSQL function "foo_tr_fun" line 5 at SQL statement
RegTAP=>