Ruby (programming language)
Ruby has been described as a multi-paradigm programming language: it allows procedural programming (defining functions/variables outside classes makes them part of the root, 'self' Object), with object orientation (everything is an object) or functional programming (it has anonymous functions, closures, and continuations; statements all have values, and functions return the last evaluation). It has support for introspection, reflection and metaprogramming, as well as support for interpreter-based threads. Ruby features dynamic typing, and supports parametric polymorphism.
Ruby License
JRuby is an implementation of the Ruby programming language atop the Java Virtual Machine. It distributes some additional libraries that are not covered by JRuby's license, like most files found in src/lib/ruby/1.8, which are distributed under Ruby license.