shadow-cljs-gjs-target

This project implements a build target for shadow-cljs so that Clojurescript can be compiled to Javascript in a form suitable for Gnome Javascript Bindings - Gjs.

Notes

This is a modification of the :node-script target from original shadow-cljs source code.
Both development and release mode compilations work.
Gjs does not have a console object. As such, a rudimentary console analog is implemented which proxies appropriate functions in Gjs. This makes Clojurescript println and related functions working as is.
Gjs builtin modules(i.e. gi.Gtk, system) are importable as Clojurescript namespaces using a special syntax.

Special syntax for importing builtin modules

Gjs builtin modules can be accessed using a string based namespace syntax - "gjs.<builtin-module-name>". For example, if you want to import the gi.Gtk module, the mapped namespace name should be "gjs.gi.Gtk".

Import syntax mapping

| Javascript | Clojurescript | | ---------- | ------------- | | const Gtk = imports.gi.Gtk; | (require '["gjs.gi.Gtk" :as Gtk]) | | const ByteArray = imports.ByteArray; | (require '["gjs.byteArray" :as ByteArray]) | | const { Gtk, GLib } = imports.gi; | (require '["gjs.gi" :refer [Gtk GLib]]) |

Tutorial

Here's a short tutorial on how to get a simple Gtk app and running with Clojurescript. Note that I am detailing the lowest friction way of installing and using shadow-cljs. Feel free to use lein, boot or deps.edn, if you want so. Look at shadow-cljs documentation to know how to do that.

Install npm with your distribution's package manager. Also, don't forget to install gjs and gobject introspection bindings, which is packaged under name gir1.2-javascriptcoregtk-4.0 in Ubuntu 20.04.
Create a demo shadow cljs project with npx create-cljs-project gjs-demo. This should create a project directory named gjs-demo. Change current directory to it.
Create a file named gjs_demo.cljs under directory src/main/ with the following content -

```clojure (ns gjs-demo (:require [clojure.string :as str] ["gjs.gi.Gtk" :as Gtk] ["gjs.system" :as system]))

(defn ^:export main [& args] (println "Hello from console!") (println "Command line arguments are: " (str/join ", " args)) (let [msg (str "Hello, Gtk + Clojurescript!\ngjs version = " (.-version system))] (Gtk/init nil) (let [win (Gtk/Window.) label (Gtk/Label. #js {:label msg})] (doto win (.add label) (.show_all)) (Gtk/main)))) ```

Edit the shadow-cljs.edn file. Change it's content to -

```clojure ;; shadow-cljs configuration {:source-paths ["src/dev" "src/main" "src/test"]

:dependencies [[titonbarua/shadow-cljs-gjs-target "0.1.0"]]

:builds {:app {:target shadow-cljs-gjs-target.core :output-to "./app.js" :main gjs-demo/main}}} ```

Run npx shadow-cljs compile app. This should emit a development javascript file named app.js at project root. Run it with gjs app.js. If everything is ok, you should see a tiny Gtk window with some text.
To produce a release build, run npx shadow-cljs release.

Related resources

Things to TODO:

Source maps don't work.
REPL does not work.
There needs to be a way to explicitly set gi versions before import, like: imports.gi.versions.Gtk = "3.0";
Needs to add tests.
Take care of undefined property errors.

License

This program and the accompanying materials are made available under the terms of the Eclipse Public License 2.0 which is available at http://www.eclipse.org/legal/epl-2.0.

This Source Code may also be made available under the following Secondary Licenses when the conditions for such availability set forth in the Eclipse Public License, v. 2.0 are satisfied: GNU General Public License as published by the Free Software Foundation, either version 2 of the License, or (at your option) any later version, with the GNU Classpath Exception which is available at https://www.gnu.org/software/classpath/license.html.