ariarule-4clojure-solution121.clj

;; ariarule's solution to Universal Computation Engine
;; https://4clojure.com/problem/121

(fn uce [formula]
  (fn [z] 
    (letfn [
            (replacer [x]
                      (if (list? x)
                        (apply (get {'/ / '+ + '- - '* *} (first x))
                               (map replacer (rest x)))
                        (if (number? x)
                          x
                          (get z x))))]
      (replacer formula))))