The JPMS represents what is probably the largest single change in Java's history. It significantly impacts the entire stack: language, libraries, and runtime/VM. In my experience the host of incompatibilities resulting from modules are not worth the trouble -- there's not much to gain from using them.<p>Generally the JPMS provide two benefits:<p>1. Since the JRE is restructured to use modules, it can be used piecemeal, which is great for embedded systems.<p>2. A module controls exposed packages -- only explicitly exported packages are accessible to dependent modules.<p>With this in mind it's difficult to justify the JPMS fallout: Why should #1 impact the much larger market of Java SE? #2 is nice, however we already have this feature with IDEs like IntelliJ IDEA, which provide robust compile-time module systems. And the runtime aspect of JPMS access control is hardly worthwhile; it's not security (reflection can always bypass that), so what is it providing exactly? Surely it doesn't fix the notorious "JAR hell" issue, you still need to shade jars or use OSGi.
Besides Spark, is there still a niche that Scala fills? Why wouldn’t you just use Kotlin or Java 11? I guess I should ask the inverse question too: why wouldn’t you just use Scala for everything?