Project Lambda: Java Language Specification draft

[Zdenek Tronicek]

Neal Gafter napsal(a):
> On Mon, Jan 25, 2010 at 8:05 AM, Zdenek Tronicek <tronicek at fit.cvut.cz>
> wrote:
>> Right. It is not specified well. However, the correction is not
>> difficult:
>>
>> SAM sam = #()(3);
>>
>> is desugared to
>>
>> SAM sam = new SAM() {
>>  public int f() { return 3; }
>> }
>
> That only works when the expression being converted is a lambda.  What
> if it is some other expression of function type?

A variable of function type?

#int() p = #()(3);
SAM sam = p;

After desugaring:

final #int() pp = p;
SAM sam = new SAM() {
  public int f() { return pp.invoke(); }
}

Or method invocation?

#int() method() { return #()(3); }

SAM sam = method();

After desugaring:

SAM sam = new SAM() {
  public int f() { return method().invoke(); }
}

> It also doesn't play well with these parts of the specification:
>
> On Fri, Jan 22, 2010 at 2:55 PM, Alex Buckley <Alex.Buckley at sun.com>
> wrote:
>> It is a goal of this document
>> to allow the implementer freedom as to how and when lambda expressions
>> are evaluated.

Freedom is fine (and you can trust me, I spent a childhood in communist
Czechoslovakia). However, one must ask here: what is the proposed freedom
motivated by? And will not it blur the semantics?

Z.
-- 
Zdenek Tronicek
FIT CTU in Prague