Why no placeholder shortcuts for lambdas?

[Richard Warburton]

> I'm wondering why the shortcuts for lambdas are not as short as they can be.
>
> For example I get the following to work:
>
> xs.foldLeft(0, (i1, i2) -> i1 + i2);
> xs.foldLeft(0, ListTest::add);
>
> static int add(int i1, int i2) {
>   return i1+i2;
> }
>
> where xs is a list of ints, foldLeft a method of this list and add a
> method in a class ListTest. But what was the design decision to disallow
> the following:
>
> xs.foldLeft(0, (+))
> // or
> xs.foldLeft(0, (_+_))
> // => (obj1).+(obj2) for objects
> // => (prim11)+(prim2) for primitives
>
> where + can be a method of an object or an operation on primitives and _
> any placeholder.
>
> Is this technically impossible or are there other reasons?

This has been discussed on the list before, the thread in
http://mail.openjdk.java.net/pipermail/lambda-dev/2011-September/004025.html
provides some comments.  My tl;dr is that the EG thought there was
very little benefit gained by this syntactic sugar for the added
complexity.

regards,

  Richard