jUCM: Universal Class Morphing (position paper)

TL;DR

jUCM introduces a pattern-based compile-time reflection language that enables universal class morphing, allowing pattern-matching over types and maintaining modular type safety, enhancing metaprogramming capabilities.

Contribution

It extends class-morphing with universal morphing, allowing pattern-matching over types while ensuring type safety, which is a novel addition to compile-time reflection tools.

Findings

Provides a disciplined metaprogramming language with type safety.

Enables pattern-matching over classes and types.

Discusses design for integrating universal morphing into Java.

Abstract

We extend prior work on class-morphing to provide a more expressive pattern-based compile-time reflection language. Our MorphJ language offers a disciplined form of metaprogramming that produces types by statically iterating over and pattern-matching on fields and methods of other types. We expand such capabilities with "universal morphing", which also allows pattern-matching over types (e.g., all classes nested in another, all supertypes of a class) while maintaining modular type safety for our meta-programs. We present informal examples of the functionality and discuss a design for adding universal morphing to Java.