On 2021-06-21 19:59 +0200, Marc Nieper-Wißkirchen wrote:
> I just noticed that the protocol of 'fxmapping-filter-map' doesn't allow
> false values to be inserted, which is ugly from a purists point of view and
> may lead to logical errors.

Yes, but of course this reflects a very common pattern in Scheme.
Since only one value is returned by fxmapping-filter-map's procedure
argument, it's quite consistent with the rest of the Scheme world to
make this a "value or #f" situation.

> ... or, in symmetry with
> 'fxmapping-unfold' just one 'skip' procedure, which aborts the current
> continuation.

I'm not sure I understand.  How would this work?

At this point, I'm inclined to leave fxmapping-filter-map alone.
It could also just be removed; analogous functions are missing
from SRFIs 146, 125, etc.

--
Wolfgang Corcoran-Mathe  <xxxxxx@sigwinch.xyz>

"A LISP programmer knows the value of everything, but the cost
of nothing." --Alan J. Perlis