IStdlib.ARListinclude sig ... endval empty : 'a tval singleton : 'a -> 'a tval of_list : 'a list -> 'a tval is_empty : 'a t -> boolval is_singleton : 'a t -> 'a optionval is_singleton_or_more : 'a t -> 'a IContainer.singleton_or_moreval hd_exn : 'a t -> 'aval last_exn : 'a t -> 'aval hd : 'a t -> 'a optionval last : 'a t -> 'a optionval fold_left : ('a t, 'a, 'accum) IStdlib.IStd.Container.foldval fold_right : ('a t, 'a, 'accum) IStdlib.IStd.Container.foldval fold_unordered : ('a t, 'a, 'accum) IStdlib.IStd.Container.foldAlways better than fold_left when you do not care about the order.