Add support for ClojureScript evaluation in the browser and building ClojureScript modules in the project

[Lambeaux]

Scope

Applies to experiment: https://github.com/connexta/osg-eyes/tree/mvn-indexing
Ensure you're familiar with the parent issue: #19

Goal

Provide JavaScript dependencies, fully integrated with the build, that do the following:

• Evaluate ClojureScript for the app's CLI.
• Support pre-loading ClojureScript so functions are readily available in the evaluation namespace.
• Support querying and retrieving metadata about the current evaluation namespace (for use in autocomplete, etc).
• Convert deps-draw-graph to .cljc, which is "platform-independent" Clojure.
• Provide a JavaScript build of deps-draw-graph for the browser's consumption.

This adds overhead to the project that must be dealt with:

• Passing around JavaScript between modules as part of the build.
• Managing the ClojureScript build process as part of Maven.

Notes

Managing ClojureScript builds as part of a maven project is a small endeavor on its own. Here are some options:

• Call the ClojureScript jar manually using an exec plugin; see ClojureScript's compiler options. Alternatively this just-maven-clojurescript-archetype pom might work better.
• Call clj using the Clojure CLI tools (see quickstart and CLI sections below) and wrap it with an exec plugin; couldn't override the out/ directory for where compiled artifacts end up so unless that gets solved this is no good.
• Use zi-cljs but it's really out of date so I didn't bother trying it.
• Use Leiningen with the lein-cljsbuild plugin and either exec Leiningen from Maven or use the lein-maven-plugin to call Leiningen as a library from Maven.
• Use shadow-cljs; doesn't seem appropriate for most of these use cases since it's more of the npm / yarn side of the ClojureScript equation. If deps-ui/ (Create base UI to serve as CLI and dependency graph explorer #20) was done in ClojureScript instead of plain JavaScript / JSX then shadow-cljs would make perfect sense for that.

Quickstart to ClojureScript:

• https://clojurescript.org/guides/quick-start

Clojure CLI tools:

• https://clojure.org/guides/getting_started#_clojure_installer_and_cli_tools
• https://clojure.org/guides/deps_and_cli
• https://clojure.org/reference/deps_and_cli

What Reddit has to say on the topic:

• https://www.reddit.com/r/Clojure/comments/77sqjw/trying_to_find_a_guide_for_leiningen_with/
• https://www.reddit.com/r/Clojure/comments/7885ox/tutorial_clojurescript_with_leiningen/

Extra stuff:

• https://github.com/pallet/lein-maven

See Adds Clojure console/repl at the top of the web page commit:

• Leverages paren-soup to provide the CLI.
• Transitive dependency on eval-soup.
• Latter commits improve the integration and expose the eval function window.clojure.eval(text, callback) for use on the React side of the project.
• Note that paren-soup is not available on NPM so the released files had to be copied into deps-ui/public manually but I was loathe to check them into source control so I did not.
• Also, paren-soup manages its HTML directly which doesn't work for a React app; to work around this I am hiding the HTML that paren-soup needs to attach to / manage to properly initialize and simply ignore it once its satisfied.
• Currently not sure how to interact with paren-soup's autocomplete or parinfer support so I suspect we'll have to do that ourselves.
• Currently cannot omit the first order opening ( and closing ) without an error getting thrown; would be nice to do this since Clojure is truly being used as just a CLI in this context and everything on the CLI is a function.