Unlambda is an obfuscated functional programming language, a sort of frightening mixture of Intercal and Scheme. The distribution includes sample programs, Unlambda interpreters and documentation. This can be useful to learn functional language programming, or how to write interpreters.
ANTLR (ANother Tool for Language Recognition) is a language tool that provides a framework for constructing recognizers, compilers, and translators from grammatical descriptions containing C++, Java, or Sather actions. It is similar to the popular compiler generator YACC, however ANTLR is much more powerful and easy to use. ANTLR-produced parsers are not only highly efficient, but are both human-readable and human-debuggable (especially with the interactive ParseView debugging tool). ANTLR can generate parsers, lexers, and tree-parsers in either C++, Java, or Sather. ANTLR is currently written in Java.
MIT/GNU Scheme is an implementation of the Scheme programming language, providing an interpreter, compiler, source-code debugger, integrated Emacs-like editor, and a large runtime library. MIT/GNU Scheme is best suited to programming large applications with a rapid development cycle. Recent versions of the system are supported on the following platforms: GNU/Linux, *BSD, OS/2, and Windows.
bigFORTH is a native code Forth. It was originally developed on the Atari ST for the Motorola 68k processor and was recently ported to Intel 386, running under a DOS extender (GO32). bigFORTH is available for Linux and Windows 95/98/NT in pre-beta-test. This version is available under GPL. The most striking new feature is the graphical user interface MINOS and the form editor Theseus. MINOS is a graphic user interface (GUI) for X, written for bigFORTH-Linux and bigFORTH-Win32. It includes a rapid GUI developement editor (Theseus).
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.