Thoughts on Racket & Chez Scheme
Chez Scheme is a well-respected implementation of the Scheme programming language that was bought by Cisco in 2012 and released under an open-source license for the first time in 2016. The following year, the Racket team announced that Racket would abandon its own C-based foundation in favor of Chez Scheme. That is, the parts of Racket that were written in C would be rewritten in Racket (where possible) or Chez Scheme (where necessary). In so doing, Racket would essentially itself become a DSL running on Chez Scheme. In 2021, that project was meaningfully finished, as the new Racket based on Chez Scheme (working title “Racket CS”) became the default version of Racket in release 8.0.
Though Chez Scheme is one of the fastest Scheme implementations, the primary motivation for the move was not performance so much as maintainability. Instead of relying on a custom pile of C code, and the ongoing maintenance costs thereof, Racket planned to hop on the back of Chez Scheme and float merrily down the river. Furthermore, because Chez Scheme is owned by Cisco—and employs Chez Scheme’s principal architect, Kent Dybvig—there’s been a sense that Chez Scheme’s own future funding & survival is already assured. So by lashing Racket to Chez Scheme, Racket would indirectly benefit from this institutional underpinning.
When I first heard about this “Racket CS” project in 2017, I didn’t spend too long thinking about it. I trusted that the Racket team had good reasons for making the switch. Whatever adjustments that would be needed down the road from Racket developers would be worthwhile.
