Doc: mention need for JavaFX

[holyjak]

I haven't run into this problem but @jeroen in Clojurians slack did

[holyjak]

Correction: I did run into the problem now I moved to OpenJDK 11 and still haven't figured out how to solve it - I have added the following to my Gradle dependencies:

  compile 'com.cognitect:REBL:0.9.218'
  compile 'org.openjfx:javafx-fxml:11.0.1'
  compile 'org.openjfx:javafx-controls:11.0.1'
  compile 'org.openjfx:javafx-graphics:11.0.1'
  compile 'org.openjfx:javafx-media:11.0.1'
  compile 'org.openjfx:javafx-swing:11.0.1'
  compile 'org.openjfx:javafx-base:11.0.1'
  compile 'org.openjfx:javafx-web:11.0.1'

but still starting the repl with gradlew clojureRepl --middleware=nrepl-rebl.core/wrap-rebl fails with

Execution error (ClassNotFoundException) at jdk.internal.loader.BuiltinClassLoader/loadClass (BuiltinClassLoader.java:583).
javafx.application.Platform

Update I have noticed the FX packages are empty. I seem to recall somebody mentioned that you should get the packages with a classifier appropriate for your OS, which doesn't seem to be happening for me (OSX).

Update 2 That 👆is indeed the case. Once I switched to the JavaFX Gradle plugin instead of adding the dependencies manually it started working. I could likely also add the dependencies for my platform explicitly: compile 'org.openjfx:javafx-fxml:11.0.1'; compile 'org.openjfx:javafx-fxml:mac:11.0.1'; ....

Update 3 For deps.edn it is enough to specify the raw packages without OS classifiers and those will be downloaded automatically. See https://github.com/seancorfield/dot-clojure/blob/48f70d5324b0d5cfcc11e8cfca1c037477d0885c/deps.edn#L95