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Setup dynamic Clojurescript and Quil environment with emacs and figwheel

My environment

  • emacs 26.3
  • cider 0.25.0
  • leiningen 2.9.4 on Java 11.0.2
  • ~/.lein/profiles.clj : {:user {:plugins []}}

Project setup

In a terminal, run these commands:

lein new quil-cljs minimal-quil
cd minimal-quil
lein figwheel
  • When figwheel is ready to connect, open a browser on http://localhost:3449
  • You should see a circle following a circular trajectory while changing its colour

simple emacs cider-connect (no cljs repl)

  • Assumes lein figwheel running properly (see project setup)

  • M-x find-file : .../minimal-quil/src/minimal_quil/core.cljs

  • M-x cider-connect

    • host: localhost
    • port for host: 3449
  • Minibuffer should display message: "[nREPL] Direct connection to localhost:3449 established"

  • Now change something in the core.cljs file (e.g. change q/ellipse to q/rect)

  • M-x save-buffer

  • You should see the ellipse change into a rectangle in the browser

more advanced cider-jack-in-cljs

  • Assumes no running lein figwheel (unlike cider-connect)
  • M-x find-file : .../minimal-quil/project.clj
  • add these dev dependencies:
...
  :profiles {:dev {:dependencies [[cider/piggieback "0.5.0"]
                                  [figwheel-sidecar "0.5.20"]]
                   :source-paths ["cljs_src"]
                   :repl-options {:nrepl-middleware [cider.piggieback/wrap-cljs-repl]}}}
...
  • Make sure the :plugins dependency of lein-figwheel is aligned with the :dev dependency of figwheel-sidecar so in this case, it should be [lein-figwheel "0.5.20"]

  • M-x find-file : .../minimal-quil/src/minimal_quil/core.cljs

  • M-x cider-jack-in-cljs

    • select ClojureScript REPL type: figwheel
  • When lein figwheel is ready to connect, open a browser on http://localhost:3449

  • The *cider-repl minimal-quil(cljs)* buffer should display a cljs.user> prompt

  • Try (+ 2 3) ; it will compile the cljs to javascript, execute it in your browser and return the result in your repl

  • Try (js/alert "Hello World!") in the repl

  • M-x find-file : .../minimal-quil/src/minimal_quil/core.cljs

  • (+ 2 3) M-x cider-eval-defun-at-point

  • You now have the dynamic environment you're used to when developing clojure in emacs

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