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Re: are lambdas a way to bring functional programming to java?

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In article <53b36f49$0$293$14726298@news.sunsite.dk>, Arne Vajhøj 
(arne@vajhoej.dk) says...

> BTW somewhat off-topic, I do not like the COMPARE_BY_LENGTH thingy.
> 
> It is almost like:
> 
> public static final int TWO = 2;

> * The name does not really explain more than the value
> * The value is given by the name so the value can never be changed
>    without changing the name

That argument applies to every method you're writing: 
* A method's name cannot explain than the code it encapsulates
* If you change what a method does, you need to change the name of the 
method.
So should we stop writing methods and just copy-paste the code to every 
corner of the program that would call it to get rid of that "problem" 
then? Of course not.
But that's exactly what you're asking for. 
Lambdas are essentially blocks of code, and the DRY principle should 
apply to them like for every other block of code.

> The paradigm actually creates more work when something has to be
> changed without improving readability.

That example is not very good in my opinion, and it doesn't compare 
well, as the right hand side in your "TWO" example doesn't do a thing 
and there is no margin for error and no benefit of reuse, ever.

No margin for error? But the other code was so simple it had none 
either.. sure, not in a string (well, there's always an NPE waiting, but 
let's ignore that), but what if your comparator looked like this:

(Amount a, Amount b) -> a.value() - b.value();

which you might think is simple enough to copy-paste everywhere...

Now imagine a.value() happened to be Integer.MIN_VALUE and b.value() 
happened to be 10 then the result would be positive, thus indiciating a 
was larger than b, which is obviously wrong. So this code, as simple as 
it is, and as obvious as it looks, has a bug. Bummer.

Now, if that block of code would have been re-used from a single 
location (like a lambda or class in a static field, a method, or so), 
then you would correct that exactly once and every code that used it 
would be happy and fixed.
If, however, you copy-pasted it everywhere, as it was "too simple to be 
beneficial", as you might say, you'd have to check every Amount#value() 
call and see if it was used in this fashion, which is a PITA and you 
don't want that.

Kind regards,
Wanja

-- 
..Alesi's problem was that the back of the car was jumping up and down 
dangerously - and I can assure you from having been teammate to 
Jean Alesi and knowing what kind of cars that he can pull up with, 
when Jean Alesi says that a car is dangerous - it is. [Jonathan Palmer]

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are lambdas a way to bring functional programming to java? gdotone@gmail.com - 2014-06-27 16:50 -0700
  Re: are lambdas a way to bring functional programming to java? Arne Vajhøj <arne@vajhoej.dk> - 2014-06-27 20:14 -0400
    Re: are lambdas a way to bring functional programming to java? Arne Vajhøj <arne@vajhoej.dk> - 2014-06-27 20:23 -0400
      Re: are lambdas a way to bring functional programming to java? Wanja Gayk <brixomatic@yahoo.com> - 2014-06-28 14:43 +0200
        Re: are lambdas a way to bring functional programming to java? markspace <markspace@nospam.nospam> - 2014-07-01 14:34 -0700
          Re: are lambdas a way to bring functional programming to java? Arne Vajhøj <arne@vajhoej.dk> - 2014-07-01 22:01 -0400
          Re: are lambdas a way to bring functional programming to java? Wanja Gayk <brixomatic@yahoo.com> - 2014-07-02 20:52 +0200
            Re: are lambdas a way to bring functional programming to java? markspace <markspace@nospam.nospam> - 2014-07-02 13:08 -0700
              Re: are lambdas a way to bring functional programming to java? Wanja Gayk <brixomatic@yahoo.com> - 2014-07-03 03:13 +0200
              Re: are lambdas a way to bring functional programming to java? Joerg Meier <joergmmeier@arcor.de> - 2014-07-06 14:42 +0200
        Re: are lambdas a way to bring functional programming to java? Arne Vajhøj <arne@vajhoej.dk> - 2014-07-01 22:27 -0400
          Re: are lambdas a way to bring functional programming to java? Arne Vajhøj <arne@vajhoej.dk> - 2014-07-01 22:32 -0400
            Re: are lambdas a way to bring functional programming to java? markspace <markspace@nospam.nospam> - 2014-07-01 19:58 -0700
            Re: are lambdas a way to bring functional programming to java? Wanja Gayk <brixomatic@yahoo.com> - 2014-07-02 22:55 +0200
              Re: are lambdas a way to bring functional programming to java? markspace <markspace@nospam.nospam> - 2014-07-02 15:32 -0700
                Re: are lambdas a way to bring functional programming to java? Gene Wirchenko <genew@telus.net> - 2014-07-03 09:45 -0700
          Re: are lambdas a way to bring functional programming to java? leif.roar@invalid.com (Leif Roar Moldskred) - 2014-07-01 23:48 -0500
            Re: are lambdas a way to bring functional programming to java? Wanja Gayk <brixomatic@yahoo.com> - 2014-07-02 22:55 +0200
              Re: are lambdas a way to bring functional programming to java? Gene Wirchenko <genew@telus.net> - 2014-07-03 09:49 -0700
                Re: are lambdas a way to bring functional programming to java? markspace <markspace@nospam.nospam> - 2014-07-03 10:25 -0700
                Re: are lambdas a way to bring functional programming to java? Gene Wirchenko <genew@telus.net> - 2014-07-04 11:03 -0700
          Re: are lambdas a way to bring functional programming to java? Wanja Gayk <brixomatic@yahoo.com> - 2014-07-02 21:23 +0200
      Re: are lambdas a way to bring functional programming to java? Roedy Green <see_website@mindprod.com.invalid> - 2014-06-30 09:08 -0700
        Re: are lambdas a way to bring functional programming to java? Arne Vajhøj <arne@vajhoej.dk> - 2014-07-01 21:56 -0400
  Re: are lambdas a way to bring functional programming to java? Joerg Meier <joergmmeier@arcor.de> - 2014-06-28 12:11 +0200
    Re: are lambdas a way to bring functional programming to java? Roedy Green <see_website@mindprod.com.invalid> - 2014-06-30 08:50 -0700
      Re: are lambdas a way to bring functional programming to java? markspace <markspace@nospam.nospam> - 2014-06-30 09:09 -0700
      Re: are lambdas a way to bring functional programming to java? Wanja Gayk <brixomatic@yahoo.com> - 2014-07-01 19:27 +0200
        Re: are lambdas a way to bring functional programming to java? Wanja Gayk <brixomatic@yahoo.com> - 2014-07-01 20:46 +0200
          Re: are lambdas a way to bring functional programming to java? Sebastian <news@seyweiler.dyndns.org> - 2014-07-01 21:52 +0200
            Re: are lambdas a way to bring functional programming to java? markspace <markspace@nospam.nospam> - 2014-07-01 14:11 -0700
              Re: are lambdas a way to bring functional programming to java? Jan Burse <janburse@fastmail.fm> - 2014-07-22 14:37 +0200
                Re: are lambdas a way to bring functional programming to java? markspace <markspace@nospam.nospam> - 2014-07-22 10:39 -0700
                Sidetrack on generics (WAS: Re: are lambdas a way to bring functional programming to java?) Daniele Futtorovic <da.futt.news@laposte.net> - 2014-07-22 20:48 +0200
                Re: Sidetrack on generics (WAS: Re: are lambdas a way to bring functional   programming to java?) Chris Riesbeck <Chris.Riesbeck@gmail.com> - 2014-07-23 12:01 -0500
      Re: are lambdas a way to bring functional programming to java? Arne Vajhøj <arne@vajhoej.dk> - 2014-07-01 21:50 -0400
  Re: are lambdas a way to bring functional programming to java? Roedy Green <see_website@mindprod.com.invalid> - 2014-07-22 04:40 -0700
  Re: are lambdas a way to bring functional programming to java? Roedy Green <see_website@mindprod.com.invalid> - 2014-07-28 09:45 -0700

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