New candidate JEP: 401: Primitive Objects (Preview)

[Brian Goetz]

> The messaging I see is:
>    Optional = old, slow, memory-hop
>    Optional.val = new, fast, flattened

This is a somewhat cartoonish simplification of the messaging. 
Simplifications are great for understanding the broad goals, and as 
cartoonish simplifications go, it's accurate enough, but we should be 
aware of when those simplifications start to get in the way. Migration 
is a a more advanced use case, and requires a more refined perspective, 
because you're trading off more things and making finer sub-distinctions 
within the cost model.

This illustrates one of the hazards of our approach; to justify such a 
big change to the platform, we have to at least have a credible story to 
fill in all the corner cases, but what then invariably happens is that 
minority features invariably command much more attention than they 
should.  (This is in part because, if you've not spent thousands of 
hours swimming in this, it's not yet obvious what is tail and what is 
dog, and also, the tail is usually where the ugliest syntax lies, which 
invariably attracts our attention.)

 >  and as such, I would naturally use Optional.val in the API methods.

I think you need to consider that your intuitions of what you would 
"naturally" do are not yet informed by any actual experience with this 
programming model, and perhaps you should ascribe a little less 
confidence to what you would "naturally" do when confronted with a more 
subtle challenge like this.

More inquiry, less certainty.


On 3/20/2021 4:40 AM, Stephen Colebourne wrote:
> On Sat, 20 Mar 2021 at 02:02, Brian Goetz <brian.goetz at oracle.com> wrote:
>>> When reading the proposal I see that in the feature we will get code like:
>>>
>>> Optional.val<User> findUser(...)
>> This is not what we anticipate.  I would expect that for migrated types,
>> public interfaces would continue to use Optional (alias for
>> Optional.ref); we'd mostly only see Optional.val inside of private
>> implementation, where things actually hit the heap.
> Why do you anticipate that?
>
> The messaging I see is:
>    Optional = old, slow, memory-hop
>    Optional.val = new, fast, flattened
> and as such, I would naturally use Optional.val in the API methods.
>
> Stephen