Re: Immutable Datastructures with good Sharing

I haven't read/followed the whole OP Thread discussion but I thought it was
worth mentioning/recommending the Google "Guava Project":
http://code.google.com/p/guava-libraries/

I think they really "went to town" on that one. You have strongly typed
Immutable Collection definitions for all Java Collection types e.g.
ImmutableMap.Builder, ImmutableList.Builder. The design is awesome e.g. the
Builder pattern as prescribed in Effective Java (last edition) and the
performance gains are noticeable as well e.g. In a distributed system I have
been working on lately, switching the attribute instances of the DTO Beans
from ArrayList Java Collection to use instead the implementation from Guava
gave some noticeable 15-20% Serialization performance gain e.g. Test case
involving 1-Echo-Server and 1K-Clients.

I really enjoy the improvement in code readability as well, it suits the
appropriate template types e.g.

// from
List<RequestData> requests = new ArrayList<RequestData>();

// to
List<RequestData> requests = Lists.newArrayList();

Guava really rocks! Would this be the Java Collections design debt now
finally paid by Joshua Bloch?