arityErr :: Outputable a => String -> a -> Int -> Int -> SDoc
arityErr kind name n m
= hsep [ text kind, quotes (ppr name), ptext (sLit "should have"),
- n_arguments <> comma, text "but has been given", int m]
+ n_arguments <> comma, text "but has been given",
+ if m==0 then text "none" else int m]
where
n_arguments | n == 0 = ptext (sLit "no arguments")
| n == 1 = ptext (sLit "1 argument")