e3 is a full-screen, user-friendly text editor with an interface similar to that of either WordStar, Emacs, Pico, Nedit, or vi. It's heavily optimized for size and independent of libc or any other libraries, making it useful for mini-Linux distributions and rescue disks. The assembler version supports Linux, FreeBSD, OpenBSD, NetBSD, Win9x, QNX, Atheos, BeOS, ELKS, and DOS. There is also a separately distributed version written in C which supports some other Unix versions and CygWin. It is also possible to use regular expressions by using child processes like sed. e3 has a built in arithmetic calculator.
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.
CodeGuide is a lean and fast IDE for Java and JavaServerPages. It features on-the-fly error checking, incremental background ("instant") compilation, powerful refactoring capabilities, and support for generic types. A visual debugger with on-the-fly class replacement (HotSwap) is also included.
GNU TeXmacs is a free wysiwyw (what you see is what you want) editing platform with special features for scientists. The software aims to provide a unified and user friendly framework for editing structured documents with different types of content: text, mathematics, graphics, interactive content. TeXmacs can also be used as an interface to many external systems for computer algebra, numerical analysis, and statistics. New presentation styles can be written by the user and new features can be added to the editor using Scheme.
Boxes is a text filter that can draw any kind of box around its input text. Box design choices range from simple boxes to complex ASCII art. A box can also be removed and repaired, even if it has been badly damaged by editing of the text inside. Since the generated boxes may be open on any side, the program can also be used to create regional comments in any programming language. New box designs of all sorts can easily be added and shared by appending to a free format configuration file. In addition to being a command line tool, Boxes integrates well with any text editor that supports filters.