You can search for identifiers within the package.
in-package search v0.2.0
include S.TIME
val now : unit -> int32
type fd
include S.RW with type handle := fd
include S.ASYNC
type 'a t
val (>>=) : 'a t -> ('a -> 'b t) -> 'b t
val fail : exn -> 'a t
val return : 'a -> 'a t
val really_read : fd -> int64 -> Cstruct.t -> unit t
val really_write : fd -> int64 -> Cstruct.t -> unit t
val exists : string -> bool t
val openfile : string -> bool -> fd t
val fsync : fd -> unit
val create : string -> fd t
val close : fd -> unit t
val get_file_size : string -> int64 t
val get_modification_time : string -> int32 t
val lseek : fd -> int64 -> Unix.seek_command -> int64 t
val lseek_data : fd -> int64 -> int64 t
val lseek_hole : fd -> int64 -> int64 t