(run! proc coll)
Runs the supplied procedure (via reduce), for purposes of side effects, on successive items in the collection. Returns nil
(run! prn (range 5))
; 0
; 1
; 2
; 3
; 4
; returns nil
; compared to mapv
(mapv prn (range 5))
; 0
; 1
; 2
; 3
; 4
; returns [nil nil nil nil nil]