R. Kent Dybvig, professor emeritus of Computer Science at Indiana University, now with Cisco, has recently open sourced version 9.4 of his formerly commercial Scheme compiler Chez Scheme.
Chez Scheme is an optimizing compiler that generates native code for the PowerPC, SPARC, IA–32, and x86–64 architectures. It supports Scheme R6RS, the 2007 Scheme standard that is supported by many Scheme implementations available today, such as Racket, Ikarus, Larceny and Ypsilon. Chez Scheme uses incremental native compilation and focuses on maximizing programmer productivity as well as application reliability and performance, according to its creator.
Chez Scheme is compiled using a nanopass compiler, which strives to reduce the number of transformations and optimizations that are done in a single pass to just one. This approach is claimed to make a compiler easier to understand and maintain, while also simplifying development, testing, and debugging. As an additional consequence of this, Chez Scheme should be particularly interesting for studying purposes.
Chez Scheme has a sibling interpreted implementation, known as Petite Chez Scheme, which uses a high-speed threaded interpreter design. Programs written for Chez Scheme may be run in Petite Chez Scheme. The only exception to this is represented by programs using foreign function interface (FFI) and other language features only available with the compiler. With the open sourcing of Chez Scheme, though, it is not entirely clear what role can Petite Chez Scheme play, since it was meant as a way to freely distribute programs written in Chez Scheme for anyone who could not justify purchasing Chez Scheme.
Dybvig is also the author of the freely available The Scheme Programming Language
Chez Scheme is available on GitHub and can be built on Linux, OS X, and Windows.
