In the recent weeks, both of my co-bloggers told me independently of each other about Groovy, the new hipster language which brings the scripting goodness of dynamic languages like Ruby and Smalltalk to the JVM Sweet JVM, so I finally couldn’t resist but take a look at it. To be honest, I didn’t like its Java-like syntax from the beginning, with all the parentheses, lowerCamelCaseIdentifiers and such, but that was just because I prefer Ruby’s very lean syntax. Its concepts are very close to Ruby (modification of objects and classes at runtime, blocks/closures, etc.) and of course it integrates well with the Java platform and its rich libraries, since this is the purpose for which it was created, to add a scripting facility to the Java platform. Groovy scripts are compiled into bytecode before execution and thus run on a normal JVM.
A crucial part for dynamic languages today (at least in my eyes) is the creation of domain-specific language, which Groovy also supports. Gant, for example, is a Groovy DSL for Ant scripts. Another example (take from the Tutorial Domain-Specific Languages in Groovy, PDF) I find very practical is a DSL for creating query criteria for Hibernate in the Grails framework (formerly known as Groovy on Rails, so its purpose should be clear):
def c = Account.createCriteria()
def results = c {
like("holderFirstName", "Fred%")
and {
between("balance", 500, 1000)
eq("branch", "London")
}
maxResults(10)
order("holderLastName", "desc")
}
A good thing, but looks too java-y for my taste, I miss the feeling I get when using a Ruby DSL, such as SQL-DSL, for example:
statement = Select[:column1, 'book', 10].from[:table1, :table2].where do
equal :column1, 99
not_equal :column1, 100
less_than :column2, 'foo'
less_than_or_equal :column3, :column4
greater_than :column1, 0
greater_than_or_equal :column2, 'bar'
like :column1, 'any'
is_not_null :column1
is_in :column1, [1,2]
is_not_in :column2, [3, 4]
exists 0
not_exists 0
end
But maybe that’s just personal preference.
From a few first glance I get the impression, that Groovy is quite successful as a scripting sidekick to Java and I’m curious to learn more about it.
Filed by Magnus at 2:55 pm under 
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