Create Domain-Specific Languages with ANTLR

he concept of Domain-Specific Languages (DSLs) has been around for years, but has recently experienced an uptick in popularity. This is due in large part to the success of Ruby on Rails, which exploits the Ruby programming language and its meta-programming capabilities to encourage the development of programs that closely mirror the domains they model. This style of DSL is sometimes called an internal DSL because it uses available constructs from the programming language itself to create code that reads in a manner similar to the underlying domain. Here are a couple of examples of internal DSLs:

 // Ruby - Active Record for Object Relational Mapping
class Book < ActiveRecord::Base
belongs_to :category
has_many :chapters
end
// Java - Using JUnit 4.4 for verifying unit test assertions
assertThat(list, hasItems("foo", "bar", "baz"));