I've decided to exclude exception->either from this SRFI completely, especially as the implementation is non-trivial.

On Sun, Jun 14, 2020 at 11:42 AM Marc Nieper-Wißkirchen <xxxxxx@nieper-wisskirchen.de> wrote:
NB: Chibi has a `raise' here: https://github.com/ashinn/chibi-scheme/blob/0efa071672184936741640bb9d06012c7bdbb596/lib/scheme/misc-macros.scm#L35
Therefore, it does not implement what's in the appendix.

I have to blame myself. I just checked the history of Chibi. Four years ago, I asked Alex to change `raise-continuable' into `raise' because there was an erratum #17 of the R7RS.  But that erratum had to be errated itself (by removing it), but Chibi still has the version according to erratum #17.

(Alex, I included you in this post.)

The confusion came from an erratum from R6RS in §7.1 ([1]).

So we see that `guard' does exactly the right thing. It would be a bad sign if it couldn't be used to implement `either-guard' because in that case it would do the wrong thing with respect to continuable exceptions.