Lambda and intersection types

Brian Goetz brian.goetz at oracle.com
Mon Nov 12 12:06:11 PST 2012


Yes.  i2 should be an instance of both I1 and I2.

On 11/12/2012 3:01 PM, Boaz Nahum wrote:
> Yes, but should it be valid code ?
>
> If yes, I2 implements both I1 & I2 or just I2 ?
>
> Thanks
> Boaz
>
>
>
> On Mon, Nov 12, 2012 at 9:55 PM, Brian Goetz <brian.goetz at oracle.com
> <mailto:brian.goetz at oracle.com>> wrote:
>
>     The back-end work for intersection-typed lambdas is not implemented
>     yet...only the compiler front-end work.
>
>
>     On 11/12/2012 2:45 PM, Boaz Nahum wrote:
>
>         The follwing simple code ...
>
>         ==============================__======
>         interface I1 {void f();}
>
>         interface I2 {
>
>               void printMe()default { System.out.println("I2");}
>
>               void f();
>         }
>
>         public static void main(String[] args) {
>
>                   I2 i2 = (I1 & I2) () -> {};
>
>                   System.out.println( "i2 is I2=" + (i2 instanceof I2));
>
>                   i2.printMe();
>               }
>         ==============================__===
>         Output is:
>
>         ------------------------------__-------
>         i2 is I2=false
>         Exception in thread "main"
>         java.lang.__IncompatibleClassChangeError: Class
>         question.lambda_intersection___types.Q$$Lambda$2 does not
>         implement the
>         requested interface question.lambda_intersection___types.I2
>         ------------------------------__-------
>
>         What is the correct behavior ?
>
>


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