Open Source Scheme Programming Languages

Chez Scheme is both a programming language and an implementation of that language, with supporting tools and documentation. As a superset of the language described in the Revised6 Report on the Algorithmic Language Scheme (R6RS), Chez Scheme supports all standard features of Scheme, including first-class procedures, proper treatment of tail calls, continuations, user-defined records, libraries, exceptions, and hygienic macro expansion. The Chez Scheme implementation consists of a compiler, run-time system, and programming environment. Although an interpreter is available, all code is compiled by default. Source code is compiled on-the-fly when loaded from a source file or entered via the shell. A source file can also be precompiled into a stored binary form and automatically recompiled when its dependencies change. Whether compiling on the fly or precompiling, the compiler produces optimized machine code, with some optimization across separately compiled library boundaries.

Racket is a general-purpose programming language and an ecosystem for language-oriented programming. This repository holds the source code for the core of Racket plus some related packages. The rest of the Racket distribution source code is in other repositories, mostly under the Racket GitHub organization. Racket programmers typically program with functions, records, objects, exceptions, regular expressions, modules, and threads. That is, instead of a “minimalist” language, which is the way that Scheme is often described, Racket offers a rich language with an extensive set of libraries and tools. Libraries are not restricted to exporting values, such as functions; they can also define new syntactic forms. In this sense, Racket isn’t exactly a language at all; it’s more of an idea for how to structure a language so that you can extend it or create entirely new languages.