> On Apr 25, 2021, at 7:34 AM, Amirouche Boubekki <xxxxxx@gmail.com> 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).

You mean a Scheme implementation that is hosted on top of Scheme?  This could be added to Gambit’s universal backend that currently targets multiple dynamic languages (JavaScript, Python, PHP, Ruby, …).  Adding Scheme as a backend should be easy!  It wouldn’t even require the host Scheme system to support proper tail calls and first class continuations… Imagine running Scheme threads on any Scheme system!

Anyone interested in doing this is welcome to contact me...

Marc