This is pretty exciting... I've used them all libraries at this point in my career: CGLib, ASM, BCEL, ByteBuddy, Javassist, etc... each has its pluses and minus

This is pretty exciting... I've used them all libraries at this point in my career: CGLib, ASM, BCEL, ByteBuddy, Javassist, etc... each has its pluses and minuses. I've designed everything from profiling agents, to systems that pack decimals into EBCDIC and invoke COBOL programs on big IBM iron, to lightweight JIT compilers, all using these libraries. > In 2002, the visitor approach used by ASM seemed clever I couldn't agree more. The visitor pattern was very hard to explain/justify back then, and still difficult to explain to newbie programmers just entering the profession. Looking at the examples, I think this is going to be an official replacement for ASM, meaning it's going to be pretty low level. The use of streams pretty straightforward. If anyone from the JEP is reading this: I have two pieces of feedback! First, take some inspiration from the way CDI Portable Extensions work. This is probably the most delightful extension API I've ever used. The @Observe callbacks are super simple to explain to people and it's really easy to write extensions for the framework. Next, I wouldn't ignore the need for a higher-level API akin to ByteBuddy or Javassist. Sometimes I just want to write an interpreter or intercept a method call and thats it. For example in my Junit/Mockito extension https://github.com/exabrial/mockito-object-injection https://github.com/exabrial/mockito-object-injection I need to intercept a call to the class under test in order to lazily inject dependencies at the last possible moment. While I certainly could do this with ASM, Javassist makes this fairly simple with it's MethodHandler api. Side note, it's a damn shame we don't have a mobile operating system that is JVM native :/ All this cool APIs simply never reach a huge number of devices.