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Bigloo Bigloo is an implementation of the Scheme programming language. It relies on an optimizing compiler from Scheme to C. Bigloo enables connections between Scheme code and C code. It proposes many extensions to Scheme such as a regular parser compiler, an lalr parser compiler, pattern matching, an object layer, etc.

Chicken CHICKEN is a simple Scheme-to-C compiler supporting the language features as defined in the 'Revised^5 Report on Scheme'. It supports full tail-recursion and first-class continuations. The code it generates is quite portable; compiled files generated by it (including itself) should work with either no or minor changes on other systems. Linking to C modules and C library functions is straightforward, and compiled programs can easily be embedded into existing C code. The package includes many extra libraries.

DrScheme 'DrScheme' is a graphical environment for developing programs using the Scheme, MzScheme, and MrEd programming languages. Features include source text highlighting of syntax and run-time errors, support for multiple levels of Scheme from beginner to advanced, an algebraic stepper for the beginner language, interactive and graphical static analysis, a graphical user interface (GUI) library, objects, threads, modules, exceptions, TCP/IP, regular expressions, and filesystem support.

FreeSnell FreeSnell is a program which computes optical properties of multilayer thin-film coatings. Dielectric, metallic, and granular metallic films are supported. The FreeSnell package includes a SCM script (program) "nk" to create, manage, and query a refractive-index spectral database. FreeSnell is an application of the SCM Scheme implementation and the WB B-tree database package.

GOOPS GOOPS is the object-oriented extension to Guile. It is very close in spirit to CLOS (the Common Lisp Object System) but is adapted for the Scheme language. The GOOPS extension gives the user a full object oriented system with multiple inheritance and generic functions with multi-method dispatch. Furthermore, the implementation relies on a true meta object protocol, in the spirit of the one defined for CLOS. This package has been folded into guile; please see that entry (http://directory.fsf.org/guile.html) for the latest information.

Gauche 'Gauche' is an R5RS Scheme implementation that ia meant to be a handy tool for daily work. Its goals include quick startup, a built-in system interface, and native multilingual support. It has an object-oriented system similar to STklos and Guile. It natively supports UTF-8, EUC-JP, and Shift-JIS multibyte encodings.

Glame The GNU/Linux Audio Mechanics project will be a complete sound editor for GNU/Linux systems. GLAME so far has a graphical frontend to set up filter networks and perform basic audio editing tasks. A Scheme-based command line editor offers low-level access for scripting purposes.

Guile An implementation of the Scheme programming language built to be used as an extension language. It's a library you can link into your programs. Your program has full access to the interpreter's data structure, so you can extend Guile with your own primitives, datatypes, and syntax, and tailor the language to your application. It also lets more people use your language, as they needn't learn the internals of your app. They just need to understand the language and the primitives you've provided, and they can trade and share ideas by passing around scripts without you. It has arrays, lists, modules, objects, first class functions, and garbage collection.

Guile-dbi 'guile'-dbi is a generic database interface for Guile that provides a way to use database drivers that are linked at run-time.

Guile-gnome This packages includes the glue code necessary to make GNOME accesible from Guile so it provides a convenient interface for Scheme programmers to develop visual applications. This program includes the Guile-gtk bindings for Gtk+.

Guile-gtk Guile-Gtk makes the Gtk+ 1.2, Gdk Pixbuf, Glade and Gtk GL graphical user interface libraries available to Guile Scheme programmers. Complete GUI applications can be written using Guile Gtk, using both the high level Gtk widgets and the low level Gdk drawing.

Hobbit Hobbit is a Scheme to C compiler, originally written for SCM. It compiles all R4RS (with the exception of mutual tail recursion and hygienic macros) and some SCM specific stuff, and supports defmacros.

Mit-scheme 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.

Qscheme Qscheme is a fast and small implementation of Scheme written in C. It is easy to interface with dynamic libraries (since most of the external functions and variables can be declared directly in Scheme, without any special C coding) and should be easy to use as an extension language. Qscheme supports foreign function call and dynamic library. A Perl-like regular expression module is provided as an example. Benchmarks show that it is generally between 2 and 70 times faster than other scheme interpreters. It now intergrates GTK/libglade bindings. other features include efficient error and exception handling with catch/throw, support for UNIX scripting, native multithreading support, modular programming support, and a new socket interface so you can build a simple client/server on TCP/IP.

SCM SCM is a Scheme implementation that conforms to Revised5 Report on the Algorithmic Language Scheme and the IEEE P1178 specification. Scm is written in C and runs under *nix and similar systems.

SIMSYNCH The design files are comprised of Scheme definitions and expressions. These design files can be run as a Scheme program at high speed. The design files can also be translated into formats suitable for logic compilers (MACHXL, Verilog, and VHDL). SIMSYNCH simulates blocks of synchronous logic, signals whose states change simultaneously on a clock signal transition. Each block also has a reset signal, which forces all signals to the state specified in the design file. SIMSYNCH can simultaneously simulate multiple blocks with different clocks and resets. Devices can contain multiple blocks; Blocks can span multiple devices.

SISC SISC (second Interpreter of Scheme Code) is an extensible Java-based interpreter of the algorithmic language Scheme. It uses modern interpretation techniques and handily outperforms all existing Java interpreters (often by more than an order of magnitude). In addition, SISC is a complete implementation of the language. The entire R5RS Scheme standard is supported, with no exceptions. This includes a full number tower including complex number support and arbitrary precision integers and floating point numbers, proper tail recursion, and full support for first-class continuations (not just escaping continuations as in many other interpreters).

STklos 'STklos' is a Scheme system that conforms 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 to 'STk', a Scheme interpreter tightly connected to the Tk toolkit.

Scheme 48 Scheme 48 is a Scheme implementation written based on a byte-code interpreter and designed to be used as a testbed for experiments in implementation techniques and as an expository tool.

Skribe Skribe is a text processor. It is a general purpose text processor that is best suited to writing technical documents such as Web pages or technical reports, API documentation, etc. While it looks like a markup language such as HTML, so there is no need for computer programming skills to use it, it is actually a true programming language based on Scheme, and with high-level features (such as objects, higher order functions, regular and syntactic parsing, etc.). It is the successor of Scheme Scribe.