FTR: JVM Lang Summit presentation

John Rose john.r.rose at oracle.com
Tue Aug 5 07:55:18 UTC 2014


http://cr.openjdk.java.net/~jrose/pres/201407-JVMEvolution.pdf

This includes a big segment on value types.

Key slide:

What is a value, for computers?

* Any indication of quantity or quality, something like a symbol.
  – Chosen from a fixed set of alternatives (dynamic range, alphabet).

* Values can be recorded and copied at negligible cost. – Like written letters. Unlike clay tokens or coins.

* All such values (symbols) can be resolved to bits. (Shannon, 1948) – They also occupy channels: Clay, paper, media, ether, cache lines.

* In the setting of the JVM, a managed pointer, after “new”, is a value
  – pre-existing managed pointer = special kind of bits.



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