First Loki

Brian Goetz introduces new OpenJDK project ‘Valhalla’

JAXenter Editorial Team

Goetz proposes heroic effort to tackle language extensions for the Java language and JVM.


Brian Goetz has formally proposed a new OpenJDK project, going by the name of  Valhalla. Although the name brings to mind images of long dead heroes, this project is very much about catalysing major innovations in the future.

And, for the Java community at least, there’s also the very real possibility that, through this initiative, extensions to the Java language and Java virtual machine could be achieved. According to the Oracle Language Architectural Kahuna, this corresponding code repositories will be available soon.

March of the Value Types

A subproject of Valhalla, which goes under a similar class, both faceless and unchangeable (immutable) value types or ‘ValueTypes’ is another feature signposted by Goetz in his keynote at JAX 2014 as “the next big target” on the roadmap for Java.

In a presentation on the introduction of Value Types  last April,  Goetz describe the efforts in this regard as follows:

“The goal of this effort is to explore how small immutable user-defined aggregate types without identity can be surfaced in the language and the JVM instruction set to support memory- and locality-efficient programming idioms without sacrificing encapsulation.

We believe that the design of the Java VM and language can be gently extended with a new kind of type, a value type, which usefully combines the properties of Java’s current classes and primitive types.”

To date, so-called “primitives” (  byte , short ,  int ,  long ,  float ,  double ,  char  and  boolean ) are the only faceless data types in Java.

The five introduced with Java generic types or generics will, with the help of Valhalla, be extended to primitive types. So far, generic types can only be made compatible with  ”Boxing” or “boxing” primitive types, which negatively affects the performance – especially after the introduction of Value Types. A first draft of the Valhalla project has been published by Goetz. Click here if you’d like a glimpse.

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