The Pre-Scheme Restoration project has made significant progress in porting the codebase to R7RS Scheme implementations. The use of “The Incomplete Scheme48 R7RS Compatibility Library” has helped maintain compatibility with Scheme 48 during the porting process. Scsh was adopted as a tooling platform for better support with filesystem and external processes. Implementing R7RS-small for Scheme 48 proved to be straightforward due to the existing functionality in Scheme 48. The project also focuses on porting the Pre-Scheme compiler macros and library definitions to ensure compatibility with the target implementations. The next steps include integrating Unsyntax as the portable expander and expanding the test coverage and documentation.
https://prescheme.org/posts/first-report-on-the-pre-scheme-restoration.html