On Tue, 9 Jun 2020, at 08:48, Marc Nieper-Wißkirchen wrote:
> (6) These macros do not handle procedures returning multiple values;
> this may not be an issue with Clojure (I don't know), but it should be
> taken into consideration with Scheme. Especially for pipelining,
> multiple values can come in handy when more than one value has to be
> threaded through (or just at some intermediate stages).

This can be done using auxiliary macros. The current implementation of as-> does not allow for it, but with my own threading macros you can do (~>> '(1 2 3) (apply values) (nth-value <> 0) (/ 5)) -> 5.

That one also addresses placeholders: we already have srfi-26 <> and <...> are perfect for this kind of thing.

That would be my suggestion, anyway.

I know that gerbil scheme has a similar macro with more magic and also some destructuring capabilities.

Sorry for the brevity. Typing on my phone.

Best regards
Linus Björnstam