User model stacking: current status

[Kevin Bourrillion]

On Wed, Jun 15, 2022 at 10:51 AM Brian Goetz <brian.goetz at oracle.com> wrote:

 - If we spelled .val as !, then switching from P[] to P![] not only
> prohibits null elements, but changes the layout and _introduces tearing_.
> Hiding tearability behind "non-null" is likely to be a lifetime
> subscription to Astonishment Digest, since 99.9999 out of 100 Java
> developers will not be able to say "non-null, oh, that also means I
> sacrifice atomicity."
>

Well, that's what you opted into when you... wait a minute...



> The link you probably want to attack is this last one, where you are
> likely to say "well, that's what you opted into when you said `non-atomic`;
> you just happen to get atomicity for free with references, but that's a
> bonus."
>

Your Kevin's Brain Emulator has gotten pretty decent over time... check
whether the next things it said were these (probably so):

A good clean Basic Conceptual Model For Novices is allowed to have a bunch
of asterisks, of the form "well, in $circumstance, this will be revealed to
be totally false", and that's not always a strike against the model. How do
we discern the difference between a good asterisk and a bad one? How common
the circumstance; how recognizable as *being* a special circumstance; how
disproportionate a truth discrepancy we're talking about; etc.

I know I've said this before. If I'm in a class being taught how this stuff
works, and the teacher says "Now unsafe concurrent code can break this in
horrible ways, and in $otherClass you will learn what's really going on in
the presence of data races" ... I feel fully satisfied by that. I know I
won't get away with playing fast and loose with The Concurrency Rules; I'm
not advanced enough and might never be. (Many people aren't but *don't *know
it, and therein lies the problem, but do we really have much power to
protect such people from themselves?)

I could be wrong, but I suspect this kind of viewpoint might be more common
and respected in the wider world than it is among the rarefied kind of
individuals who join expert groups, no offense to anyone here meant. You're
always going to see all the details, and you're always going to *want* to
see all the details. The general public just hopes the details stay out of
their way. When they don't, they have a bad day, but it doesn't mean they
were better served by a complex model that tried to account for everything.


-- 
Kevin Bourrillion | Java Librarian | Google, Inc. | kevinb at google.com
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://mail.openjdk.org/pipermail/valhalla-spec-observers/attachments/20220615/d6f56d86/attachment.htm>