On Friday, October 12, 2001, at 02:43 PM, Alan Kay wrote:

>      The main source of outside ideas was Dave Fisher's thesis (A 
> Control Definition Language CMU 1970). This was not object-oriented 
> (but I found it to be the logical complement to my thesis of the very 
> same period) and Dave had cast it in terms of a McCarthy-like eval in 
> itself, so it was very understandable. It had most of the things we've 
> always wanted in messaging systems.

I obtained this particular thesis from CMU a while ago, and am still 
somewhat unclear as to what in particular you are refering to.  The only 
thing I can think of is the "multiple sequential control" section.

>      I think after Carl heard about Smalltalk in Nov 72, and saw some 
> of the examples, he was able to come up with some valuable 
> characterizations of control structures and objects. Unfortunately for 
> posterity, neither the PARC group or the MIT group really was able to 
> implement a practical enough version of the deeper scope of these 
> ideas. (Part of the problem is that something like zero-overhead, large 
> number of processes are needed to really do the job.)

Are these characterizations in the 77 paper?  (Yet another one to hunt 
down...)

> Recently Andreas Raab has done some remarkable experiments with very 
> large numbers of very low overhead processes in Squeak which bodes well 
> for the future.

I am still not quite sure for what specific problems large numbers of 
processes are a good solution.  Computing propagation patterns 
on-the-fly and interleaved with the computation carried out by the 
message payload may be one case, but many/most practical cases seem to 
be solvable without the need for concurrency.

Marcel

--
Marcel Weiher				Metaobject Software Technologies
marcel at metaobject.com		www.metaobject.com