In this talk, David Nolen demos using Krell to have two REPLs, running on separate devices, with separate state, using the same code base. https://youtu.be/3HxVMGaiZbc?t=2054 is something similar supported by shadow-cljs?

@pez what do you mean specifically? this is pretty much the default of how shadow-cljs works? only that you only need one process and not 2 separate ones?

you can connect as many devices as you want and/or run as many builds in parallel as you want (or your machine can tolerate)

Yes, I do that often. But can I control which REPL I am connected to?

yeah thats a bit manual at the moment since no editor (wink, wink) has added support for manual selection yet

quick overview you can check is http://localhost:9630/runtimes

I’ll be happy to add it to Calva.

it'll list all the runtimes and their id

and when you can pick when when you start the repl via (shadow.cljs.devtools.api/repl :the-build-id {:runtime-id 123})

the id is also logged on startup by the runtime shadow-cljs: #4 ready!

I’ve seen those. 😃

there is also (shadow.cljs.devtools.api/repl-runtimes :the-build-id) to get the data from the REPL without the UI

[{:since #inst"2021-08-14T06:20:06.623-00:00",
  :proc-id "3133b4c9-82b9-4144-a0dc-68e8daddfdae",
  :connection-info {:remote true, :websocket true},
  :client-id 4,
  :user-agent "Chrome 537.36 [Win32]",
  :type :runtime,
  :lang :cljs,
  :build-id :browser,
  :host :browser,
  :dom true}
 {:since #inst"2021-08-14T06:20:07.205-00:00",
  :proc-id "3133b4c9-82b9-4144-a0dc-68e8daddfdae",
  :connection-info {:remote true, :websocket true},
  :client-id 5,
  :user-agent "Chrome 537.36 [Win32]",
  :type :runtime,
  :lang :cljs,
  :build-id :browser,
  :host :browser-worker,
  :dom false}]

from my test build that also has a webworker connected (which you can also REPL into)

I renamed some stuff so its :client-id from that list

Thanks! I'll play some with this. Great stuff!

I get a lot of #X ready! messages, with increasing id numbers. (And the id:s are bumped accordingly.) I’m using the :react-native target and have started a web and an iOS client. Looks like so after a while:

= web
#5 ready!
#7 ready!
#8 ready!
#10 ready!
#12 ready!
#14 ready!
#16 ready!
#17 ready!
#20 ready!

= iOS Simulator
#4 ready!
#6 ready!
#9 ready!
#11 ready!
#13 ready!
#15 ready!

[{:connection-info
  {:remote true,
   :websocket
   true},
  :since
  #inst "2021-08-14T08:45:55.502-00:00",
  :host
  :react-native,
  :type :runtime,
  :lang :cljs,
  :build-id :app,
  :proc-id
  "165ac90e-ac63-4516-9453-3c49e4f85815",
  :client-id 15}
 {:connection-info
  {:remote true,
   :websocket
   true},
  :since
  #inst "2021-08-14T08:53:30.446-00:00",
  :host
  :react-native,
  :type :runtime,
  :lang :cljs,
  :build-id :app,
  :proc-id
  "165ac90e-ac63-4516-9453-3c49e4f85815",
  :client-id 20}]

the ready message you get when the websocket connects. if that disconnects it'll attempt to reconnect, which gives you a new id

don't know why you'd get that many though. never seen that before. is it constantly reconnecting the websocket or does that actually have that many websockets open?

the only problem I remember was with android and react-native. that didn't disconnect the websocket when reloading the app. don't know if thats still a thing

I can test that.

> is it constantly reconnecting the websocket or does that actually have that many websockets open? Don’t know if this answers it, but if select an old id, I get no complaints, but when evaluating I get this message

The previously used runtime disappeared. Will attempt to pick a new one when available but your state might be gone.

It seems that the :since doesn’t change. Can I rely on that, as long as the app is not reloaded?

yeah, so the longer backstory to all of this: I built shadow.remote as the default remote mechanism for shadow-cljs. even the UI uses that to do everything it does. All REPLs use it. so ideally any editors would also directly connect to the shadow.remote endpoint. part of shadow.remote is a notification for when a runtime connects or disconnects

the editor would then be supposed to handle that and inform the user in some form of UI or auto select the next one etc

the regular REPL however is stuck in a block Read with no way to ask the user what they want to do

Can I read about the remote API somewhere?

so I had to compromise in picking the next one that arrives. however that logic doesn't apply if you specified one

could be considered a bug I guess 😛

https://github.com/thheller/shadow-cljs/blob/master/doc/remote.md docs are sparse at the moment

very simple EDN (transit-encoded) messages over a websocket for now

tap> and the inspect UI runs over shadow.remote, so anything the UI displays you have access to as well

Using this I can solve the old issue with Calva not really knowing when the REPL is available.

yes

It does make shadow-cljs very special from Calva’s POV, but may well be worth it to create a nice UI/Ux.

a shadow.remote over nrepl would be possible as well if that helps

just as a transport layer I mean. don't know how well that would integrate into your nREPL code though as the message flow is a bit different. usually nrepl doesn't push messages to the client without receiving a request first

but yeah all the extra ops you get are shadow-cljs specific

I’d love me a shadow.remote over nrepl. Calva has ways to deal with “orphaned” incoming messages, so I should be able to weed out the ones from shadow/remote there.

well the messages you'd get are all marked as such, so "op" "shadow.remote" or so. haven't really looked into it too much yet

the thing I don't like about nrepl is that there is no explicit connection management. so you don't know when a connection starts or ends from the middleware perspective

As for the android react-native client. It doesn’t disconnect at app reload, as you remembered. It is cleaned away after a few seconds though. Both iOS and web disconnect immediately before reconnecting.

yeah I added that cleanup specifically for android RN

I’m trying to use react-bootstrap with shadow-cljs and I’m requiring like so

(:require ["react-bootstrap" :as bs])

Image: {$$typeof: Symbol(react.forward_ref), defaultProps: {…}, render: ƒ}
InputGroup: {$$typeof: Symbol(react.forward_ref), Text: {…}, render: ƒ, Radio: ƒ, Checkbox: ƒ, …}
ListGroup: {$$typeof: Symbol(react.forward_ref), Item: {…}, render: ƒ}
ListGroupItem: {$$typeof: Symbol(react.forward_ref), defaultProps: {…}, render: ƒ}
Modal: undefined
ModalBody: undefined
ModalDialog: undefined
ModalFooter: undefined

Is there a way to output to the root directory? expo EAS requires the entry point to be a root level index.js file. I can make it work by copying shadows build/index.js to the root level and then doing a find/replace to fix the paths in the file, so is there a reason why shadow wouldn’t allow you to do this automatically?

@alex395 do this instead https://github.com/thheller/reagent-react-native/blob/master/react-native/index.js. :output-dir "." might also work but not recommended, no guarantee that shadow-cljs won't overwrite a file that you might need for something. preferable to have its own directory that you can delete at any point

:target :esm might also be an option. been a while since I looked at react-native stuff, see https://clojureverse.org/t/generating-es-modules-browser-deno/6116