demo won't compile

[glyh]

Here's relevant lines in my dune-project file:

(pin (package (name riot)) (url "git+https://github.com/riot-ml/riot"))
(pin (package (name rio)) (url "git+https://github.com/riot-ml/rio"))
(pin (package (name gluon)) (url "git+https://github.com/riot-ml/gluon"))
(pin (package (name bytestring)) (url "git+https://github.com/riot-ml/bytestring"))

(package
 (name ochain)
 (synopsis "A simple blockchain implemented in OCaml")
 (description "A simple blockchain implemented in OCaml")
 (depends 
   ocaml 
   dune
   (cryptokit (>= 1.20))
   (yojson (>= 2.2.2))
   (ppx_deriving_yojson (>= 3.9.0))
   (batteries (>= 3.8.0))
   riot)

And the example:

open Riot

type Message.t += Hello_world

let () =
  Riot.run @@ fun () ->
  let pid =
    spawn (fun () ->
        match receive () with
        | Hello_world ->
            Logger.info (fun f -> f "hello world from %a!" Pid.pp (self ()));
            shutdown ())
  in
  send pid Hello_world

OCaml complains this:

Entering directory '/home/lyh/Documents/Knowledge/CS/PL/Experiments/ochain'
File "bin/main.ml", lines 9-12, characters 8-23:
 9 | ........match receive () with
10 |         | Hello_world ->
11 |             Logger.info (fun f -> f "hello world from %a!" Pid.pp (self ()));
12 |             shutdown ().
Error (warning 8 [partial-match]): this pattern-matching is not exhaustive.
Here is an example of a case that is not matched:
*extension*
Matching over values of extensible variant types (the *extension* above)
must include a wild card pattern in order to be exhaustive.

[linear]

RIOT-37 demo won't compile

[glyh]

RIOT-37 demo won't compile

Why can't the explaination just be hosted on github?