Ciao is a complete Prolog system subsuming ISO-Prolog with a novel modular design which allows both restricting and extending the language. Ciao extensions currently include feature terms (records), higher-order, functions, constraints, objects, persistent predicates, a good base for distributed execution (agents), and concurrency. Libraries also support WWW programming, sockets, and external interfaces (C, Java, TCL/Tk, relational databases, etc.). An Emacs-based environment, a stand-alone compiler, and a toplevel shell are also provided.
Onyx is a powerful stack-based, multi-threaded, interpreted, general purpose programming language similar to PostScript and Forth. It can be embedded as an extension language into other applications, and was designed to have a small memory footprint. It is among the smallest embeddable interpreters available.
Q is a powerful and extensible functional programming language based on the term rewriting calculus. When programming with Q, you specify a system of equations which the interpreter uses as rewrite rules to reduce expressions to normal form. Q is useful for scientific programming and other advanced applications, and also as a sophisticated kind of desktop calculator. The distribution includes the Q programming tools, a standard library, add-on modules for interfacing to various third-party libraries, and an Emacs mode.
Gforth is a fast and portable implementation of the ANS Forth language. It works nicely with the Emacs editor, offers some nice features such as input completion and history and a powerful locals facility, and it even has (the beginnings of) a manual. Gforth employs traditional implementation techniques: its inner innerpreter is indirect or direct threaded. Gforth runs under Unix, Win95, OS/2, and DOS and should not be hard to port to other systems supported by GCC.
STklos is a free Scheme System conforming to R5RS. The implementation is based on an ad-hoc Virtual Machine. It can also be compiled as a library, so that one can easily embed it in an application. Its features include an efficient and powerful object system based on CLOS, a simple-to-use module system, implementation of the full tower of numbers defined in R5RS, and easy connection to the GTK+ toolkit. STklos is the successor of STk, a Scheme interpreter tightly connected to the Tk toolkit.
ROOT is an OO framework for large-scale scientific data analysis and data mining. It contains an efficient hierarchical OO database, a C++ interpreter, advanced statistical analysis, visualization, introspection, documentation, networking, and GUI classes. The command/scripting language is C++, and large scripts can be compiled and dynamically linked in. Using the PROOF (Parallel ROOT Facility) extension, large databases can be analyzed in parallel. The system runs on all known POSIX platforms, Windows, and MacOS X.
AFNIX is a multi-threaded functional writing system with dynamic symbol bindings that support the object oriented paradigm. It has a rich set of features providing runtime compatibility with C++. The engine runs on both 32- and 64-bit platforms, and it is designed to be portable across platforms.