module type Basic2 =sig
..end
type ('a, 'e)
t
val return : 'a -> ('a, 'b) t
val apply : ('a -> 'b, 'e) t ->
('a, 'e) t -> ('b, 'e) t
val map : [ `Custom of
('a, 'e) t ->
f:('a -> 'b) -> ('b, 'e) t
| `Define_using_apply ]