val collector : out:[ `File of string ] -> unit -> Trace_core.collector
(** Make a collector that writes into the given output.
    See {!setup} for more details. *)

type output = [ `File of string ]
(** Output for tracing.
    - [`File "foo"] will enable tracing and print events into file
        named "foo". The file is only written at exit.
*)

val setup : ?out:[ output | `Env ] -> unit -> unit
(** [setup ()] installs the collector depending on [out].

    @param out can take different values:
    - regular {!output} value to specify where events go
    - [`Env] will enable tracing if the environment
      variable "TRACE" is set.

      - If it's set to "1", then the file is "trace.json".
      - If it's set to "stdout", then logging happens on stdout (since 0.2)
      - If it's set to "stderr", then logging happens on stdout (since 0.2)
      - Otherwise, if it's set to a non empty string, the value is taken
        to be the file path into which to write.
*)

val with_setup : ?out:[ output | `Env ] -> unit -> (unit -> 'a) -> 'a
(** [with_setup () f] (optionally) sets a collector up, calls [f()],
    and makes sure to shutdown before exiting.
*)

(**/**)

module Internal_ : sig
  val mock_all_ : unit -> unit
  (** use fake, deterministic timestamps, TID, PID *)

  val on_tracing_error : (string -> unit) ref
end

(**/**)