You can search for identifiers within the package.
in-package search v0.2.0
type 'a t
val fail : string -> 'a t
val ret : 'a -> 'a t
val map : ('a -> 'b) -> 'a t -> 'b t
val (>>=) : 'a t -> ('a -> 'b t) -> 'b t
val run : 'a t -> ('a, string) result
val to_err : ('a, string) result -> 'a t
val err_of_option : string -> 'a option -> 'a t