The code's internet presence is apparently gone (bitbucket mercurial. I don't know how I missed that ). I won't have access to that code for about 2 weeks, but I will upload it and try to get it up to par with the updated SRFI-158.

Lg. Linus Björnstam

On Tue, 26 Jan 2021, at 08:14, Marc Nieper-Wißkirchen wrote:
> Am Di., 26. Jan. 2021 um 08:08 Uhr schrieb Linus Björnstam
> <xxxxxx@veryfast.biz>:
> > Hi Y'all!
> >
> > I have an efficient, almost done implementation of srfi-121. I believe it lacks generator-unfold, but that is all. make-coroutine-generator is implemented using delimited continuations and runs a lot faster than the one in the reference implementation, with the caveat that it is apparently slightly incompatible: the coroutine generator usage in (srfi 146 hash) yielded the wrong result - despite my version passing all tests.
>
> Can you post a MWE?
>