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Java.net Poll on Closures

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Java.net is having a poll on which version of closures is preferred for Java 7. I think this is a great opportunity for First-Class Methods (FCM) to get some attention as a worthy contender.

Closures offer us the opportunity to make our Java code simpler by making the Java language more complex. The tradeoff is - how much simpler will our programs get, and how much more complex will the language get? I feel that First-Class Methods presents the best balance between language complexity and code simplicity.

First Class Classes

Do you ever use Class objects in your application? For example, to instantiate a logger:

public class RealDeliveryService {
  private static final Logger logger = Loggers.forClass(RealDeliveryService.class);

  ...
}`</pre>
... or to bind a type with Guice:
<pre class="prettyprint">`  public void configure() {
    bind(DeliveryService.class).to(RealDeliveryService.class);
    bind(User.class).toProvider(UserProvider.class);
    ...
  }`</pre>
Class literals are powerful, typesafe, and easy to use. FCM takes the power of Class literals and extends it to methods and fields. 

### First Class Methods

With this, much boilerplate code vanishes. Consider sorting Deliveries by price:
<pre class="prettyprint">`  List&lt;Delivery&gt; deliveries = ...
  Comparator&lt;Delivery&gt; orderByPrice = new Comparator&lt;Delivery&gt;() {
    public int compare(Delivery a, Delivery b) {
      return a.getPrice().compareTo(b.getPrice());
    }
  }
  Collections.sort(orderByPrice, deliveries);`</pre>
With FCM, we just create a comparator from the `getPrice` method:
<pre class="prettyprint">`  List&lt;Delivery&gt; deliveries = ...
  Comparator&lt;Delivery&gt; orderByPrice = MethodComparator.newInstance(Delivery#getPrice());
  Collections.sort(orderByPrice, deliveries);

FCM can dramatically reduce boilerplate throughout your application:

  • If you're writing a Swing app, you'll be able to specify a no-argument method to invokeLater, rather than defining an anonymous Runnable.
  • If you're writing a web app, FCM will lend additional typesafety to your libraries like Struts 2.
  • And FCM invites a new generation of frameworks and tools to be created. Terse like ruby, typesafe like Java.

Help FCM Gain Mindshare

Please, familiarize yourself with the proposals and vote for a better Java.