Re: how to extend a capability on a data source?

On Sun, Nov 3, 2013 at 9:05 AM, Rob Withers <[email protected]> wrote:

>
> how can one distinguish that an arg is immediate or eventual
>

E doesn't use static typing. That doesn't mean ocap languages cannot cannot
use static typing. Though, I'd not recommend Java-like types. Instead, use
structural typing, substructural typing, and dependent typing. If you want
to guarantee that a promise is completed once and only once, substructural
typing would do the job.


> I was thinking of “tracking” the send, itself, in some respects, and being
> able to manage it.
>

I can't think of any good semantics for tracking a 'send'.  I suppose you
could return a variation of a tracking number or something to the sender,
but unnecessarily asking non-deterministic questions (has the message been
processed yet?) isn't a good thing, nor would there be good (deterministic,
sensible) semantics for stopping the message.


> Could you mention the deficiencies of message passing, that is problematic
> to implementing data-flow
>

It isn't especially difficult to implement dataflow above message-passing.
That doesn't mean message passing is a good way to understand dataflow.
Indeed, I believe it would be better to formally understand message-passing
in terms of a temporal dataflow model, making the intermediate state and
ordering issues much more explicit.

Message passing, in general, has a lot of deficiencies:
http://awelonblue.wordpress.com/2012/07/01/why-not-events/

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