SAM identity or at least equals/hashCode

[Brian Goetz]

>> I think "lambda expression" is the right thing to say when you are
>> referring to the lambda itself.  It is an expression, but its type
>> is contingent on its context (it is target-typed) and undergoes a
>> conversion of sorts before it becomes a SAM.
>>
>> If you want to refer to the object instance that is the result of
>> SAM conversion, call that the SAM instance or the SAM object --
>> which is an object.  (You can't assume much about its identity --
>> the compiler will likely make sure that all instances of
>> "stateless" lambdas are really the same object, a la the
>> "Flyweight" pattern.)
>
> Only stateless? Why?

Lambdas can capture final local variables.  Consider:

public IntFactory constGenerator(int x) { return #{ -> x } };

Clients will call the resulting IntFactory with
   foo.make()
and expect an int to come back.  The SAM-converted lambda is an object,
it has to have a nilary make() method, that method has captured state x,
so where do we store the captured state?

> The question is: Will SAM objects that lambda expressions are going
> to be converted to, implement any meaningfull equals/hashCode methods
> or are those methods going to be inherited from Object (or SAM
> class).

No.

> "If a SAM type is a class type, then it must be declared abstract and
> have a no-args constructor."

Class SAMs are no longer under consideration, only interface SAMs.