Lambda and JSR 292 method handle (a prototype)

[Rémi Forax]

Le 27/12/2009 18:57, Neal Gafter a écrit :
> Rémi-
>
> In Types.java, you seem to mark most function types as reifiable, but 
> your mapping (erasure) does not in fact reify them.  Am I missing 
> something?

It's a prototype. What I would like is to implement instantiation of 
generics in function type
as a conversion that will create a new reified lambda from a generic non 
refied lambda.
But I haven't yet implement it.

I think there is also a problem with array of function types because 
they should not be reifiable.

>
> Also, your selected syntax for lambda expressions would be ambiguous 
> with shorthand invocation.  The expression "lambda()(2)" can either be 
> a lambda expression of no arguments whose result is 2, or an 
> invocation of a method named lambda with no arguments, and then 
> applying the resulting function value to the single argument 2.

No, because the prototype use .invoke() to call a function type.
lambda()(2) is a lambda expression that return 2.

An invocation of a method named lambda with no argument
that return a function type should use invoke:

private static #void(int) lambda() {
   return lambda(int x) {
     System.out.println(x);
   };
}

lambda().invoke(2);


>
> Cheers,
> Neal

Cheers,
Rémi

>
> On Sun, Dec 27, 2009 at 8:31 AM, Rémi Forax <forax at univ-mlv.fr 
> <mailto:forax at univ-mlv.fr>> wrote:
>
>     I've sketch a prototype of lambdas on top of method handle.
>     http://weblogs.java.net/blog/forax/archive/2009/12/27/chistmas-gift
>
>     The patches are here:
>     http://cr.openjdk.java.net/~forax/lambda/
>     <http://cr.openjdk.java.net/%7Eforax/lambda/>
>
>     Rémi
>
>