Any DSL that we develop with Groovy is referred to as an embedded DSL. In other words, it uses language features from the host language in order to build a new mini dialect that achieves a particular goal. As programmers, we can appreciate the elegance of how a closure can define a mini dialect that is embedded within our code. We are used to all of the boilerplate that goes with using a Java library.
By boilerplate we mean all of the setup code that is needed to establish the context in which our code is running. This could be connecting to a database, establishing a connection to a remote EJB object via a JNDI lookup, and so on. It also includes all of the other code, which is superfluous to the problem at hand but is imposed by the languages and environments that we use. The requirement in Java to write all of our code within a class is a case in point. Comparing the Groovy "Hello, World" program with its Java equivalents, we can see that all but a single line of...