Chez Scheme is both a programming language and an implementation of
that language, with supporting tools and documentation.
This variant of Chez Scheme is extended to support the implementation
of [Racket](https://racket-lang.org/).

Major additions to Chez Scheme in the Racket variant:

 * AArch64 support

 * pb (Portable bytecode) support, which is mainly useful for
   bootstrapping a build on any supported platform

 * Unboxed floating-point arithmetic and flvectors

 * Type reconstruction during optimization (especially for safe code)

 * Continuation attachments

 * Parallel garbage collection, in-place garbage collection for
   old-generation objects (instead of always copying), and
   reachability-based memory accounting

 * Ordered finalization, immobile (but collectable) objects, and
   weak/ephemeron generic hash tables
