Function types versus arrays

[Neal Gafter]

On Wed, Feb 17, 2010 at 3:10 PM, Neal Gafter <neal at gafter.com> wrote:
> On Wed, Feb 17, 2010 at 2:59 PM, Joshua Bloch <jjb at google.com> wrote:
>> I really don't understand this.  Earlier on, Alex said that we should
>> refrain from thinking too hard about the implementation at this point, and I
>> still believe that to be true.  If you could show that some interaction of
>> the proposed syntax and semantics interacted poorly with the existing type
>> system, that would be a big problem, but I haven't seen such an argument
>> that didn't presuppose a particular implementation of function types. I
>> really do think we should design the best spec (syntax and semantics) and
>> then see if it's implementable.
>
> I agree with the process you describe.  I just think we're a couple of
> steps ahead of you.  Setting aside the precise syntax, there is a
> specific problematic interaction of the currently proposed semantics
> with the existing type system, and we're exploring the fallout of that
> issue.  We don't have to wait for the syntax to be settled to explore
> the fallout of the semantics issue, and as I pointed out resolving the
> semantic issue can help guide the syntax.

I should add that Howard relaunched this thread with the idea of
relaxing Java's usual assumption that a subtype conversion preserves
the identity of the reference.  I don't think that relaxation actually
solves the problem, and it does break other things in the language.
But it is worth spending some time determining if and how it breaks.