badmaps.clj

(let [qparams {"cat" "meow"}
      parammap {"cat" #(println "feline says" %), "dog" #(println "canine says" %)}
      foundparam (into {} (filter #(contains? parammap (key %)) qparams))]
  ((get parammap (key (first foundparam))) (val (first foundparam))))
;> feline says meow

; Cleaner?
(let [queryparams {:cat "meow", :cheese "nonsense"}
      functionmap {:cat #(println "feline says" %), :dog #(println "canine says" %)}
      selectedkey (first (select-keys functionmap (keys queryparams)))]
   ((val selectedkey) (queryparams (key selectedkey))))

; Cleanest? -alex
(let [q-params {:cat "meow", :cheese "nonsense"}
      f-map {:cat #(str "feline says " %)
             :dog #(str "canine says " %)}
      [k f] (first (select-keys f-map (keys q-params)))]
   (prn (f (q-params k))))

;; WHAT DOES THE FOX SAY?
(let [qparams {:cat "meow" :cheese "nonsense" :dog "woof" :fox "nininininininini"}
      fmap {:cat #(str "feline says " %) :dog #(str "canine says " %) :rat #(str "nasty rats are gross " %)}
      fn-map (remove #(nil? (:fn (val %)))
                     (reduce (fn [m [k v]]
                               (assoc-in m
                                         [k]
                                         {:fn (fmap k) :param v}))
                             {}
                             qparams))]
  (for [[k v] fn-map] ((v :fn) (v :param))))