On Apr 1, 5:46 am, Christophe Grand <christo...@cgrand.net> wrote:
> Hello Korny,
>
> I share your questioning.
>
> On 1 avr, 06:57, Korny Sietsma <ko...@sietsma.com> wrote:
>
> > (A) one ref for the whole world - in which case how do I stop parallel
> > changes to two unrelated structures in the world from causing transaction
> > retries?
>
> In this case, I wonder whether to extend "ensure" so as to be able to
> ensure an invariant over a ref would be a good idea.
> eg:
>
> (ensure world f arg1 arg2) ; compute (f @world arg1 arg2)
> ;....
> (commute world g arg3 arg4) ; commute iff (f @world arg1 arg2) still
> returns the same value.
>
Interesting - I'll think about it. Off the top of my head I'm
concerned about the use of commute - it's not really commute if you
need to ensure that something hasn't changed. Also, there will be a
lot of pressure on the root, and need for history, even if the
mechanism avoids retries. You would only consider this if the need to
see the world as a single value dominated other concerns.
Until then, I recommend option C. Korny really has two things here -
the set (please, anything but list) of identities that constitutes the
world, and those identities themselves.
Rich
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