Does mapv not do exactly what the author needs? Ie an unlazy map?
https://clojuredocs.org/clojure.core/mapv
Clojure provides doseq and run! for side effects on collections, and both return nil. One might get the impression that these design choices are intended to discourage the programmer from complecting transformations of sequences with performing side effects on their elements.
Most of the time, you can replace one with another, such as pmap (lazy, parallel) and have the program behave the same way. Using mapv for side effects breaks this assumption.