I have the following calva connection settings in VSCode settings.json file:

"calva.replConnectSequences": [
      {
        "name": "clojure-backend",
        "nReplPortFile": [".nrepl-port"],
        "projectType": "deps.edn",
        "cljsType": "none"
      },   
      {
        "name": "clojurescript-frontend",
        "projectType": "shadow-cljs",
        "cljsType": {
            "dependsOn": "shadow-cljs",
            "connectCode": "(shadow.cljs.devtools.api/repl :app)",
        }
      }
    ],

... then I connect to backend and frontend REPLs...

For a while everything is ok. But occasionally I see in the backend terminal REPL:

ERROR: Unhandled REPL handler exception processing message {:op close, :session 5136a91c-6071-4bba-80a6-21184505df0a}
java.net.SocketException: Socket closed
	at java.base/java.net.SocketOutputStream.socketWrite(SocketOutputStream.java:113)
	at java.base/java.net.SocketOutputStream.write(SocketOutputStream.java:150)
	at java.base/java.io.BufferedOutputStream.flushBuffer(BufferedOutputStream.java:81)
	at java.base/java.io.BufferedOutputStream.flush(BufferedOutputStream.java:142)
	at nrepl.transport$bencode$fn__716.invoke(transport.clj:131)
	at nrepl.transport.FnTransport.send(transport.clj:34)
	at nrepl.middleware.session$close_session.invokeStatic(session.clj:285)
	at nrepl.middleware.session$close_session.invoke(session.clj:279)
	at nrepl.middleware.session$session$fn__1381.invoke(session.clj:322)
	at nrepl.middleware$wrap_conj_descriptor$fn__942.invoke(middleware.clj:16)
	at nrepl.server$default_handler$fn__1949.invoke(server.clj:141)
	at nrepl.server$handle_STAR_.invokeStatic(server.clj:24)
	at nrepl.server$handle_STAR_.invoke(server.clj:21)
	at nrepl.server$handle$fn__1917.invoke(server.clj:41)
	at clojure.core$binding_conveyor_fn$fn__5823.invoke(core.clj:2047)
	at clojure.lang.AFn.call(AFn.java:18)
	at java.base/java.util.concurrent.FutureTask.run(FutureTask.java:264)
	at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1128)
	at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:628)
	at java.base/java.lang.Thread.run(Thread.java:829)

misc1/foo
Syntax error compiling at (REPL:0:0).
No such var: misc1/foo

I examined this a bit more and it seems to happen when I connect to the frontend repl.

Yep. Exactly then.

This is my deps.edn : https://github.com/karimarttila/my4clojure/blob/master/deps.edn

... and shadow-cljs.edn: https://github.com/karimarttila/my4clojure/blob/master/shadow-cljs.edn

I think it might be the shadow-cljs configuration. I examine this a bit myself.

It’s because Calva cannot connect to two repls simultaneously.

As your shadow-cljs config is managed by tools.deps {:deps …} you can only connect to shadow-cljs repl to get both cljs and clj repls working

Ah, I didn't know that. Thanks!

> As your shadow-cljs config is managed by tools.deps {:deps …} you can only connect to shadow-cljs repl to get both cljs and clj repls working In fact, that’s what is happening. When you connect to what you have named “frontend”, the previous repl is disconnected and you have both backend and frontend provided by the “frontend” connection. That’s why I renamed it to “backend + frontend" in my suggestion.

Ah, ok. Let's try that.

... and I need to update my blog post regarding this. Good channel - very fast help. Thanks! 🙂

And you should post it as a separate post in #C8NUSGWG6, I think. It did not make it to this week's Clojure Deref when you hid it in a thread there.

One more question.

So, if I have this configuration in my settings.json:

"calva.replConnectSequences": [
      {
        "name": "backend + frontend",
        "projectType": "shadow-cljs",
        "cljsType": "shadow-cljs",
        "menuSelections": {
          "cljsLaunchBuilds": [
            ":app",
            ":test",
          ],
          "cljsDefaultBuild": ":app"
        }
      }
    ]

Hm. Maybe I have to continue reading the Calva documentation to fully understand this. 🙂

> is the backend REPL actually started by Calva as Jack-in? No, it’s started by shadow-cljs, as shadow-cljs started nREPL, and has all the dependencies needed for running backend code.

Calva Jack-in only starts shadow-cljs repl in this case

Ah, ok.

Hm. In Cursive you can start the backend and frontend REPLs separately in terminals, and then have two separate connections to those two REPLs. So, I guess in Calva, this means that I need to setup also the needed backend aliases in shadow-cljs.edn ?

Not exactly, look at how it’s sorted out in Luminus template:

"calva.replConnectSequences": [
        {
            "name": "my-luminus-shadow Server",
            "projectType": "Leiningen",
            "afterCLJReplJackInCode": "(in-ns 'user) (start) (println \"Access the server at \")",
            "cljsType": "none",
            "menuSelections": {
                "leinProfiles": [
                    "dev"
                ]
            }
        },
        {
            "name": "my-luminus-shadow Server + Client",
            "projectType": "shadow-cljs",
            "afterCLJReplJackInCode": "(in-ns 'user) (start) (println \"Access the server at \")",
            "cljsType": "shadow-cljs",
            "menuSelections": {
                "cljsLaunchBuilds": [
                    "app",
                    "test"
                ],
                "cljsDefaultBuild": "app"
            }
        }

Hm. Maybe I need to find some example that uses both frontend and backend REPLs and deps.edn and shadow-cljs and Calva. And then study the example and read the Calva documentation once more. I really want to understand this part properly if I start using Calva.

E.g. using that backend + frontend I can't navigate to the clojure functions any more using ctrl+mouse.

Ok. ctrl+mouse works now => I need to put all required aliases to shadow-cljs.

Yeah, it should work

If you haven't read https://blog.agical.se/en/posts/shadow-cljs-clojure-cljurescript-calva-nrepl-basics/ I think that could clear things up. When you tell shadow-cljs to use deps, what really happens is that shadow-cljs uses the clojure command to start the REPL. It will use the :aliases to create this command line.

What a nice blogpost, I haven’t seen it before, but it could save me a lot of time a couple years ago if it’d be written then ^_^

Thanks! Yeah, I was a bit late to respond to the clues I got by all the questions about this. Check the video out as well. And the comments to that video. There is a comment there with a very nice summary of the gist of the message.

Thanks for the excellent documentation and blog post. I read those in more detail and I think I have a better understanding of these pieces now.