Scalajs support

[johnynek]

would you be open to the a PR that refactored the threading and parsing to use scalajs supporting libraries so this library could be used within a web page (or nodejs) application?

I'm willing to do the work. I think it would be a few PRs, but I don't want to maintain a fork and would rather upstream the effort.

[johnynek]

To be concrete, I think a path forward would be to factor the build into a multi-project sbt build and factor out the core from the parsing and execution system, which are where the JVM dependencies are currently.

Then, within that core, I think we could publish a scala.js version of the library for users who want to build on top of princess.

[pruemmer]

That's a great initiative; sure, we would be interested in having scala.js support!
I have little experience with scala.js, but I suspect that the threading part is quite easy to fix. The main place where we currently use Java threads is the SimpleAPI, which could be converted to a single-threaded version for scala.js. (Is conditional compilation an option?)
Parsing would require a bit more work, it would be necessary (presumably) to replace java-cup with a different library. But parsing is maybe less important here.