Intent: Given a language, define a representation for its grammar along with an interpreter that uses the representation to interpret sentences in the language.
See also: PowerfulInterpreter, StatePattern, CommandPattern, BlocksInJava, DesignPatterns, DomainSpecificLanguage
http://home.earthlink.net/~huston2/dp/interpreter.html -- BrokenLink 20120414
http://wiki.cs.uiuc.edu/patternStories/InterpreterPattern -- BrokenLink 20071203