Tuesday, February 19, 2019

Video of panel discussion with Tony Hoare, Joe Armstrong, and Carl Hewitt

The video is here:
            https://www.youtube.com/watch?v=37wFVVVZlVU

In a wide ranging discussion, there were some fundamental disagreements among the panelists as follows:


  • I disagreed with Tony Hoare about using synchronous communication as the primitive because it is too slow for both IoT and many-core chips. Instead, the primitive for communication should be asynchronous sending and receiving, from which more complex protocols can be constructed. 
       Also, I disagreed with Tony about sequential actions (using ";") as being
       foundational. 
Instead, concurrent actions are foundational for digital
       systems as follows:

    • Receipt of a communication activated sending other communications
    • An Actor received one communication before it received another communication
       Consequently, a computation is a partial order of causalityTony and I
       did agree that tooling is needed for navigating the partial order. We just
       disagreed about whether sequential actions (using ";") are foundational.


       Furthermore, class hierarchies are not a suitable foundation for Scalable
       Intelligent Systems
Interfaces instead of subclassing should be used for
       IoT communication.  Also,  entities and descriptions in large ontologies do
       not fit in an object class hierarchy
, e.g., Java and C++. Subclassing is
       not secure because it allows a subclass to impersonate a superclass.

  • I disagreed with Joe Armstrong about requiring use of external mailboxes because they are inefficient in both space and time.
    Instead of requiring an external mailbox for each Actor, buffering/reordering/scheduling should be performed inside an Actor as required.
Of course, Tony and Joe made other great points with which we agree entirely.