Stack-based (are first class objects, double-ended), object-oriented, multithreaded (POSIX), interpreted, garbage collected, general purpose, similar to PostScript; embedable as extension language. Downloads, documents. Open source, BSD.
Dynamically typed, stack-based language; has optimizing native compiler, automatic memory management, generational garbage collector, collections library, advanced features: higher-order programming, continuations, extensible syntax.
Wikipedia: Data-structured Language
Online encyclopedia article providing an overview of this type of programming language.