Single Abstract Method for SAMs cannot be polymorphic

[Brian Goetz]

A generic SAM is not a valid target type for a lambda, but it may be one 
for a method reference.

You *can* have generic (polymorphic) SAMs.  You just cannot initialize 
them with lambdas.  Use method refs instead.

(BTW, lambda support in IntelliJ is very impressive but still new, so 
there are bound to be differences between what IntelliJ accepts and what 
javac does.)

On 4/2/2013 4:16 PM, Grégoire Neuville wrote:
> I meant 'the annotation *in itself* is marked as erroneous' : so does the
> code '(a, g) -> new Gen<>()'.
>
> Note though that the sole annotation (i.e if 'CoArbitrary<?> coArb = (a, g)
> -> new Gen<>();' is commented) doesn't prevent the code from being compiled
> by javac : should it ?
>
>
> On 2 April 2013 22:04, Grégoire Neuville <gregoire.neuville at gmail.com>wrote:
>
>> Hi all,
>>
>> The below code :
>>
>> public class TestGenericSAM {
>>
>>    class Gen<B> {}
>>
>>    @FunctionalInterface
>>    interface CoArbitrary<A> {
>>      abstract <B> Gen<B> coarbitrary(A a, Gen<B> g);
>>    }
>>
>>    void test() {
>>      CoArbitrary<?> coArb = (a, g) -> new Gen<>();
>>    }
>> }
>>
>> doesn't compile. I guess this is by design (the annotation alone is marked
>> as erroneous by IntelliJ), but I'm just wondering why.
>>
>> Thanks a lot for any explanation !
>>
>> --
>> Grégoire Neuville
>>
>
>
>