Plpgsql and cursors

hi,

i'm testing postgresql database and especially the procedural language
plppgsql.
I want to 'translate' an Oracle pl/sql procedure which looks like this :

create function cal_montant_ht_com(id_com int8) RETURN NUMBER
is

cursor cur1 is select quantite_detcom,prix_ht_detcom
from detail_commandes where
fk_commande_detcom=id_com;
quantite_detcom NUMBER;
prix_ht_detcom NUMBER;
montant_ht NUMBER;

begin

montant_ht:=0;
OPEN cur1;
LOOP
FETCH cur1 INTO quantite_detcom, prix_ht_detcom;
EXIT WHEN cur1%notfound;
montant_ht:=montant_ht+(quantite_detcom*prix_ht_detcom);

END LOOP;
close cur1;
RETURN (montant_ht);

end cal_montant_ht_com;

I try this :

create function cal_montant_ht_com(int8) RETURNS float8 AS '

cursor cur1 is select quantite_detcom,prix_ht_detcom from
detail_commandes where fk_commande_detcom=$1;
quantite_detcom int8;
prix_ht_detcom float8;
montant_ht float8;

begin

montant_ht:=0;
OPEN cur1;
LOOP
FETCH cur1 INTO quantite_detcom, prix_ht_detcom;
EXIT WHEN cur1%notfound;
montant_ht:=montant_ht+(quantite_detcom*prix_ht_detcom);
END LOOP;
close cur1;
RETURN montant_ht;

END;
' LANGUAGE 'plpgsql';

but it still doesn't work (error at line 2, the declaration of the
cursor) and haven't any other idea;

Could you help me ?

olivier Allain.