Invariable

Invariables ,variables. Two of the mostly basic concepts in algorithm analysis.
After 2 years work, I deeply believe, these two are also a basic feature of the entire IT world.
Take Java world as an example. Many new technologies emerges every year, and nearly all are from basic ideas. Grovvy(http://onestepback.org/articles/groovy/whatisgroovy.html):

Groovy is …

• A Dynamic
  • Agile
    • Scripting
      • Programming Language
        • based on the JVM

is a dynamic language. The concept of dynamic language is old.
Grail a web frame work on top of Groovy, just as rail on ruby.(That's why called grail) So prepared and embrace the change.