Toptal
The Scala language has continued to gain popularity over the last several years, thanks to its excellent combination of functional and object-oriented software development principles, and its implementation on top of the proven Java Virtual Machine (JVM).
Creating a language that compiles to Java bytecode requires a deep understanding of the inner workings of the Java Virtual Machine. To appreciate what Scala’s developers have accomplished, it is necessary to go under the hood, and explore how Scala’s source code is interpreted by the compiler to produce efficient and effective JVM bytecode.
Source: Toptal