On 1/5/23 06:11, siiky wrote:
There are some things I would still use SRFI 42 for, at least for now
that I'm new to transducers. For example:

(list-ec (:list x lst1)
           (:list y lst2)
           (if (even? (* x y)))
           (cons x y))

Which is similar to  (filter even (map * lst1 lst2))  but more
performant because there's no intermediate list. I have no idea how to
do this with transducers.

I think the easiest way for this would be to just zip the list together:

    (transduce list-fold
                 (zip-list lst2)
                 (filter (lambda (p)
                           (even? (* (car p) (cdr p))))))

Jeremy Steward

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