Valhalla Reflection: Challenges and Solutions for Java Generics

Explore the intricacies of Project Valhalla's impact on Java reflection in this 37-minute conference talk by Maurizio Cimadamore at the JVM Language Summit 2016. Dive into the structural and operational layers of reflection, examining challenges posed by generics and type annotations. Discover the proposed solutions for Valhalla reflection, including specialized generics and the concept of "one mirror to rule them all." Learn about the potential changes to java.lang.Class, source reflection, and the java.lang.model package. Analyze member lookup examples, generic method lookup, and the proposed mirror taxonomy. Gain insights into specialization support and open issues surrounding Project Valhalla's reflection implementation.

Intro
Structural layer
Operational layer
Reflection and VM languages
Hello reflection
Generics & reflection - a (bad) straw hut
The hut is shaky
Type annotations - a straw too far?
The hut collapses
Valhalla specialized generics - desugared
Valhalla - some reflection challenges
Three goals for Valhalla reflection
Double down on .I. Class
What about source reflection?
double down on j.l.model
Solution #2
one mirror to rule 'em all Having separate abstractions for declarations and types is cleaner
Mirror taxonomy
Specialization support
Member lookup - example
Generic method lookup
Solution 3
Open issues