You can search for identifiers within the package.
in-package search v0.2.0
type 'a t = ('a, exn) Core.Result.t Async.Deferred.t
val return : 'a -> 'a t
val fail : exn -> 'a t
val bind : 'a t -> ('a -> 'b t) -> 'b t
val catch : (unit -> 'a t) -> (exn -> 'a t) -> 'a t