Removes all elements matching a predicate, except the last one

remove-all-but-last.clj

(defn remove-all-but-last
  [pred coll]
  (let [[_ count index] (reduce #(if (pred %2)
                                   [(inc (% 0)) (inc (% 1)) (% 0)]
                                   [(inc (% 0)) (% 1) (% 2)])
                                [0 0 nil]
                                coll)]
    (if (> count 1)
      (keep-indexed #(and (or (not (pred %2)) (= index %1) nil) %2) coll)
      coll)))

(defn butlast-pred
  [pred coll]
  (let [tgts (filter pred coll)]
    (remove #(and (pred %) (not= % (last tgts)) ) coll)))