Connecting to an out-of-process nREPL server and a merged Figwheel-main build

[danieroux]

As discussed with @PEZ on Slack:

• We start nREPL out-of-process and then connect to it
• We start figwheel-main with merged builds

The README.md in this repo explains the ideal workflow: https://github.com/danieroux/calva-clojurescript-usage

The less magic, the better ;-)

[danieroux]

We structure builds this way:

• common.cljs.edn is the base setup, for cljs.main, annotated with some Figwheel options that does not come into play for cljs.main.
• min.cljs.edn adds minification
• some-domain.com.cljs.edn is a production deploy to that domain, with all its flags twiddled and variables set for prod.

This allows us to do this for a production deploy, as a merged build:

clojure -M --main cljs.main --compile-opts common.cljs.edn --compile-opts min.cljs.edn --compile-opts some-domain.com.cljs.edn --compile

Only vanilla cljs.main, no Figwheel required. Stable, clean, clear.

So for development we merge common.cljs.edn and local.cljs.edn. And local.cljs.edn has preloads, and development toggles on. That's how we start Figwheel in dev then, by merging those two:

(defn start-cljs-repl []
  (let [read-build (figwheel.main.api/read-build "common" "local")
        build-id   (:id read-build)]
    (try
      (figwheel.main.api/start {:mode :serve} read-build)
      (figwheel.main.api/cljs-repl build-id)
      (catch RuntimeException _e
        (println "The build is already running, connection to the REPL only")
        (figwheel.main.api/cljs-repl build-id)))))

[PEZ]

Thanks. It is strange that the built-in Figwheel Main sequence doesn't work for connecting to local in that repro-repo. I don't really understand what goes wrong.

Anyway, I pushed a PR to that reoro, containing a custom repl connect sequence, that simply calls your (start-cljs-repl) there. It looks like so:

  "calva.replConnectSequences": [
    {
      "name": "My local build",
      "projectType": "deps.edn",
      "cljsType": {
        "dependsOn": "Figwheel Main",
        "connectCode": "(start-cljs-repl)",
        "isConnectedRegExp": "To quit, type: :cljs/quit",
        "buildsRequired": false,
      }
    }
  ]

Not sure the last two settings there are required. You can experiment with removing them and see if it works anyway.