Re: News for Java?
zn???rt wrote:
For instance, lambda expressions are a nice thing to have, but aren't at all a
necessity. Maybe the newest hot topic, but not a new concept at all: they
have been around for decades already in some programming languages, to
good use. Most other have done (and willl continue to do so) perfectly well
whithout. Then again lambda expressions are an example of something
relatively easy to add to a language with little or no impact on its syntax, so
thumbs up.
Wanja Gayk wrote:
I second that. You can get along without them, some of us have spent a
decade without it and Java was prospering well without, but Lambda
Expressions are, in my point of view, very valuable. They make it
concise to approach a problem in a more functional way and that is very
good for code reuse and maintainability. Just think about all the
incompatible SAM-Types. How many different predicate/filter/matcher-
classes may there be, who just evaluate an object and return true of
false? You find yourself in situations where you use a "Predicate" from
apache.commons.Collections and to re-use it for your DB4O-database you
start writing a wrapper and whatnot.
A third dimension of the closures discussion is its personality fit with Java.
In principle closures are a useful adjunct to Java's core design philosophy.
The difficulties that keep it postponed are not clear to me, but I reason
that there must still be debate and technical obstacles.
http://download.java.net/jdk7/docs/
You can track how things change, and how quickly, by documents such as
http://cr.openjdk.java.net/~briangoetz/lambda/lambda-state-3.html
For example, it shows an evolution of lambda expression syntax
from 2009-12-10:
#()(42)
#(int x)(x + 1)
to 2010-07-06:
{ -> 42 }
{ int x -> x + 1 }
to 2010-10-10:
#{ -> 42 }
#{ int x -> x + 1 }
and the nilary lambda syntax
#{ 42 }
..
The "simplification rules are based on the expectation that many lambda
expressions will be quite small". [op. cit.]
--
Lew
Ceci n'est pas une pipe.