I Wrote a Scheme in 2025

I Wrote a Scheme in 2025

One year minus one week ago to the day I published an article announcing the new Scheme implementation I was writing, scheme-rs. Today I am excited to announce that scheme-rs has reached its first version, 0.1.0 . You can check it out at it’s website ( scheme-rs.org , which should be updated to scheme.rs at some point when DNS propagation finishes) or its github page.

Although there’s much more work to do (and I will talk about that further down the page), after reaching the milestone of completing 2258 tests in the R6RS test suite, I’ve decided that scheme-rs is stable enough to commit to a first release.

It’s been a pretty amazing journey, one that I’m excited to continue on.

Changes since I initially announced scheme-rs last year:

There have been some changes since I initially announced scheme-rs. The biggest is that it is no longer exclusively async, and now supports sync as well.

This change was inevitable; only supporting async would really hamper adoption (or more importantly my personal use cases for the project). But I’m really happy that I was able to implement this change without hamstringing async support at all. In fact, it is even possible to use scheme-rs in both async and sync contexts.

Things that are not finished

There are quite a few things that are not quite complete, and I will list them here:

The garbage collector has quite a bit of room for improvement.

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