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.
Petite Chez Scheme is a freely distributable interpreted version of Chez Scheme, a high-performance implementation of ANSI Scheme with numerous extensions. Petite Chez Scheme may be used as a run-time environment for compiled Chez Scheme applications or as a stand-alone Scheme system. With the exception that the compiler is not present, Petite Chez Scheme is completely compatible with Chez Scheme.
Sizzle is a Scheme interpreter for embedding into C applications and for standalone scripting. It implements a nearly complete subset of R5RS Scheme, adding a lot of primitives for U*ix scripting, regular expression searching, a simple module system, dynamic library linking, powerful string processing procedures, and much more. It includes a user's guide and an embedding manual in texinfo format, some examples, the embedding library, and a standalone interpreter for interactive use and scripting.
Scsh is a systems-programming environment for POSIX systems and Win32, embedded in the Scheme programming language. It includes a high-level process notation for writing shell-script like programs, with pipelines and redirections. Scsh additionally provides low-level access to POSIX primitives, plus important non-POSIX extensions such as sockets. Scsh is implemented on top of Scheme48, a portable bytecode implementation of Scheme. A number of user-contributed extensions are available, including an extensible HTTP and FTP server, a socket-level PostgreSQL interface, a programmable text formatting language, and a Postscript generation language.
FramerD is a semi-structured object database integrated with a Scheme-based scripting language which supports multi-lingual programming (with pervasive Unicode), a stable module system for programming in the large, distributed applications (via an extensible RPC protocol), non-deterministic (PROLOG-like) evaluation for search and set operations, multi-threaded program execution, extensive tools for text and language analysis, built-in HTML/XML/MIME parsers, and intuitive (CGI- and FastCGI-based) Web scripting. The built-in object database robustly supports millions of objects and indexed access to those objects, both through disk files and networked servers.