filter one vector based on applying the predicate to a different vector, in clojure.

filter-by-other.clj

  (defn filter-by-other 
    [target test pred]
    (let [pairs (map vector target test)]
      (mapv first (filter #(pred (second %)) pairs))))
    
; filters target based on applying pred to test.  probably will blow up with infinite sequences, and god only knows what will 
; happen with lazy ones.  Assumes target and test are vectors of equal length, pred is a single-arity function 
;
; EXAMPLE:
; (filter-by-other [:a :b :c :d] [1 2 3 4] even?)
; => [:b :d]