Telemetry is a lightweight library for dynamic dispatching of events, with a focus on metrics and instrumentation. Any OCaml library can use telemetry to emit events, then application code and other libraries can then hook into those events and run custom handlers.
Install from Opam:
opam install telemetry
Create some events in your library or application code:
type Telemetry.event += Web_request_done of { latency: int }
Telemetry.emit (Web_request_done { latency = 10 });And now attach listeners:
Telemetry.attach (fun ev ->
match ev with
| Web_request_done {latency} ->
Printf.printf "Web request took %sms" latency
| _ -> ()
);