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Re: Why is that in JDK8: value used in lambda expression shuld be effectively final?

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On 04/01/13 22:38, Peter Duniho wrote:
> I can't speak for the previous poster.  But clearly, closures don't do
> anything you _can't_ do using lambdas or even using some other technique.
>
> The point is convenience, expressiveness, readability, and other code
> authoring and maintenance such as may be of concern are affected.  In the
> view of closure proponents (such as my own), these concerns are addressed
> in a positive way when closures are available.

Indeed.  I'm interested in seeing how much expressiveness (etc) is lost 
when one is forced to work around the lack of a feature, by looking at 
specific cases.


> But that's the point: lambdas, closures, etc. offer a more concise,
> expressive way of representing certain algorithm approaches.  In this
> context, I can confirm that there are plenty of examples of situations
> where a true closure offers a more convenient, improved way of achieving
> the same desired result, as compared to language syntax without closures.


Do these examples fall into just a couple of categories, in terms of the 
guarantees that the user of a function object makes to the provider 
about how it will be invoked?:

 1. The object will be invoked on the same thread that provided it (e.g.
    in an event-driven environment)
 2. (1) + the object will not be invoked once the call that provided it
    has completed (e.g. in control abstraction)

...or are there more, especially ones which make fewer or alternative 
guarantees?

I'm genuinely interested to see if there are more categories.  Then, if 
they are limited, could a set of type qualifiers express these 
guarantees formally, and allow compilers to progressively switch on 
features like mutable local capture and various transparencies safely?

-- 
ss at comp dot lancs dot ac dot uk

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Re: Why is that in JDK8: value used in lambda expression shuld be effectively final? jeti789@web.de - 2013-01-02 07:08 -0800
  Re: Why is that in JDK8: value used in lambda expression shuld be effectively final? jeti789@web.de - 2013-01-02 07:52 -0800
  Re: Why is that in JDK8: value used in lambda expression shuld be effectively final? Steven Simpson <ss@domain.invalid> - 2013-01-02 17:33 +0000
    Re: Why is that in JDK8: value used in lambda expression shuld be effectively final? Saxo <jeti789@web.de> - 2013-01-02 11:31 -0800
      Re: Why is that in JDK8: value used in lambda expression shuld be effectively final? Lew <lewbloch@gmail.com> - 2013-01-02 12:52 -0800
        Re: Why is that in JDK8: value used in lambda expression shuld be effectively final? Arved Sandstrom <asandstrom2@eastlink.ca> - 2013-01-02 20:58 -0400
          Re: Why is that in JDK8: value used in lambda expression shuld be effectively final? Lew <lewbloch@gmail.com> - 2013-01-02 17:40 -0800
            Re: Why is that in JDK8: value used in lambda expression shuld be effectively final? Arved Sandstrom <asandstrom2@eastlink.ca> - 2013-01-03 20:43 -0400
        Re: Why is that in JDK8: value used in lambda expression shuld be effectively final? Saxo <jeti789@web.de> - 2013-01-02 23:44 -0800
          Re: Why is that in JDK8: value used in lambda expression shuld be effectively final? Patricia Shanahan <pats@acm.org> - 2013-01-03 07:57 -0800
            Re: Why is that in JDK8: value used in lambda expression shuld be effectively final? Lew <lewbloch@gmail.com> - 2013-01-03 13:22 -0800
              Re: Why is that in JDK8: value used in lambda expression shuld be effectively final? Patricia Shanahan <pats@acm.org> - 2013-01-03 16:14 -0800
      Re: Why is that in JDK8: value used in lambda expression shuld be effectively final? Steven Simpson <ss@domain.invalid> - 2013-01-02 21:46 +0000
        Re: Why is that in JDK8: value used in lambda expression shuld be effectively final? Lew <lewbloch@gmail.com> - 2013-01-02 17:35 -0800
        Re: Why is that in JDK8: value used in lambda expression shuld be effectively final? Saxo <jeti789@web.de> - 2013-01-03 02:13 -0800
          Re: Why is that in JDK8: value used in lambda expression shuld be effectively final? Saxo <jeti789@web.de> - 2013-01-03 06:45 -0800
            Re: Why is that in JDK8: value used in lambda expression shuld be effectively final? Steven Simpson <ss@domain.invalid> - 2013-01-04 21:32 +0000
              Re: Why is that in JDK8: value used in lambda expression shuld be effectively final? Peter Duniho <NpOeStPeAdM@NnOwSlPiAnMk.com> - 2013-01-04 14:38 -0800
                Re: Why is that in JDK8: value used in lambda expression shuld be effectively final? Steven Simpson <ss@domain.invalid> - 2013-01-04 23:45 +0000
                Re: Why is that in JDK8: value used in lambda expression shuld be effectively final? Peter Duniho <NpOeStPeAdM@NnOwSlPiAnMk.com> - 2013-01-04 17:24 -0800
                Re: Why is that in JDK8: value used in lambda expression shuld be effectively final? Steven Simpson <ss@domain.invalid> - 2013-01-05 13:20 +0000
              Re: Why is that in JDK8: value used in lambda expression shuld be effectively final? Saxo <jeti789@web.de> - 2013-01-05 01:50 -0800
                Re: Why is that in JDK8: value used in lambda expression shuld be effectively final? Steven Simpson <ss@domain.invalid> - 2013-01-05 11:21 +0000
                Re: Why is that in JDK8: value used in lambda expression shuld be effectively final? Saxo <jeti789@web.de> - 2013-01-05 04:27 -0800
                Re: Why is that in JDK8: value used in lambda expression shuld be effectively final? Steven Simpson <ss@domain.invalid> - 2013-01-05 12:58 +0000

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