On 4/25/21 7:34 AM, Amirouche Boubekki wrote:

> As far as I know there is no Scheme implementation that can run on a
> trivial subset of Scheme (that is maximally portable across Scheme
> implementations and Operating Systems), and that is easy to debug
> (breakpoints, step debugger, variable inspection, one step macro
> expansion).

I'm actually working on this! My in-progress Scheme dialect (working
title: Tangled Scheme) has this as its primary goal. It will include a
full language server, linter, and debugger for R7RS Scheme, with
exhaustively-detailed error messages in the style of Rust or Elm.

I don't know if a maximally-simple "reference implementation" of Scheme
is possible, though, although writing one as an interpreter in R7RS
itself would make sense. iirc that's what Marc Nieper-Wißkirchen's
Unsyntax is.