JavaSkript is a WIP transcompiler, trying to compile English text to Java bytecode.
Updating this with everything done would be tedious, the easiest way to check
what has been done is by looking at the integrated tests
located in
modules/(module)/src/integrationTest
At the time of writing, the parser is mostly done, the api is mostly finalized, and the translator is a WIP.
Hopefully, exactly the same as normal Skript. Another goal in mind is independence from Bukkit, with a bukkit module providing a loader for Bukkit, and a java module providing a loader for Java.
The current planned system will break current addons, but it will make the Skript API a thousand times more usable (hopefully).
The only new restriction imposed is that all compile-time addons must be purely functional, and cannot reference other classes in the addon unless it is in a purely functional way.
It is important to note the differences between compile-time and runtime addons. Runtime addons are addons that the script output jar depends on at runtime, such as Spigot or Vault. The addon code in Runtime addons doesn't have to be purely functional, because the output jar just calls the method, but the addon must be present at runtime.
In practice, runtime addons are only needed when adding Skript support to another program which is designed to run without Skript.
Compile-time addons, on the other hand, will be "shaded" into the compiled jar. They must be purely functional, but they can reference other purely functional methods/fields/etc... (which will be shaded in also).
Now addons can add string addons and literal addons.
String addons are detected in strings, and allow additional string functionality (like expressions in strings, color codes in strings, etc...).
Literal addons add custom literals, such as numbers or even strings themselves. They are like expressions, except with greater control over the parsing and checked last.
Addons can also override anything they can register. This is useful for stuff like the Bukkit module overriding the Java module's "on script load" def.
Defs have to interact with key/values using transformers and headers. Defs have a main method that will be shaded in and a transform method to specify where the method will be shaded to. Defs can interact with the passed key/values such as calling instructions or running certain code if a value is true