Groovy - Do More With Less (Code) - Talk Slides from Vancouver's 1st Groovy/Grails Meetup

Some slide highlights:

Why Groovy? What’s wrong with Ruby (JRuby), Python (Jython), or Smalltalk (Bistro)?

Why yet another scripting language?

1. Groovy uses a Java-like syntax; easy to switch from Java to Groovy or from Groovy to Java
2. Groovy builds on (reuses) the Java standard class library; Ruby, Python or Smalltalk include their own batteries (that is, standard libraries)
3. 3. Groovy compiles straight to standard Java bytecode; you can use groovyc as an alternative compiler to javac

What is Java?

1. Java is a (systems) programming language (syntax).
2. Java is a “standard” class library.
3. Java is a bytecode runtime (virtual machine).

Conclusion #1, #2, #3: Groovy is Java

Groovy is Java

Groovy Standard Class Library Types == Java Standard Class Library Types

• A Groovy String is a Java String:

$ hello = "Hello" 
$ hello.class

=> java.lang.String

• A Groovy List is a Java List:

$ list = [ "Vancouver", "Ottawa" ]
$ list.class

=> java.util.ArrayList

• A Groovy Map is a Java Map:

$ map = [ "Vancouver":"British Columbia", "Ottawa":"Ontario" ]
$ map.getClass()

=> java.util.LinkedHashMap

Groovy Joint Compiler

Compiles Groovy and Java code; can handle any dependency cycles Use the -j compiler switch to enable the joint compilation. Example: Country.groovy:

class Country
{
   String name
   String capital

   String toString() { return "The capital of ${name} is ${capital}." }
}

World.java:

public class World
{
  public static void main( String args[] )
  {
    Country canada = new Country();

    canada.setName( "Canada" );
    canada.setCapital( "Ottawa" );

    System.out.println( canada.toString() );
  }
}

Let’s joint compile the Groovy and Java source.

$ groovyc -j Country.groovy World.java 

That’s it. Run it.

$ java World

=> The capital of Canada is Ottawa.

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