return-from-lambda viewed as dangerous, good alternatives

[Neal Gafter]

On Thu, Jan 7, 2010 at 10:56 AM, Stephen Colebourne <scolebourne at joda.org>wrote:

> > Having said that, I believe CfJ 0.6 a&b <http://www.javac.info>
> > illustrate that there is not necessarily a conflict between the two
> > goals, as they can be achieved concurrently.
>
> It is one suggestion. There are others, which I outlined.
>

No, you didn't outline any alternative ways of supporting transparency.  You
outlined two alternative ways of supporting nonlocal transfers without
transparency, and your third option was, basically "worry about it later".

 I didn't go into detail, because thats not the point. I hope you would
> accept that items #2 and #3 on my list (new syntax/language feature) can
> be fully transparant, as they don't exist today.
>

No, I don't accept that, not without enough of the design being done today
to ensure that it is a consistent extension.  That, by the way, was my
primary purpose for publishing CfJ 0.6 a/b.

The point I'm arguing is that the lambdas as described in the straw-man,
> and as proposed for inclusion should be non-transparant.


It isn't clear why nontransparency should be a goal.

And further,
> that because they capture return, they won't ever be transparent.


It isn't clear why expression lambdas should capture return.  There's
nothing in the current strawman to hint at that.