Several versions of Fibonacci using Clojure

Testing.clj

(ns sandbox.Testing)


; Trivial version
(def fib
  ( fn [x]
    (if (< x 2) x
    (+ (fib (dec (dec x))) (fib (dec x))))))

; Add some memoization
(def fib_mem
  ( memoize
    ( fn [x]
      (if (< x 2) x
      (+ (fib_mem (dec (dec x))) (fib_mem (dec x)))))))

(def fib_matching_mem
  (memoize
    (fn [n]
      (cond
        (= n 0) 0
        (= n 1) 1
        :else (+ (fib_matching_mem (- n 1))
                (fib_matching_mem (- n 2)))))))

(defn fib_map [n]
  (last (take (+ n 1)
    (map first (iterate (fn [[a b]] [b (+ a b)]) [0 1])))))

(def fib_complex
  (lazy-cat [0 1]
    (map + fib_complex (rest fib_complex))))



(print "Fib, 20: ") (time (fib 20))
(print "Fib Mem, 20: ") (time (fib_mem 20))
(print "Fib Matching, 20: ") (time (fib_matching 20))
(print "Fib Matching Mem, 20: ") (time (fib_matching_mem 20))
(print "Fib Map, 20: ")(time (fib_map 20))

(println (fib_map 20))
(println (fib_matching_mem 20))
(println (fib_matching 20))
(println (fib_mem 20))
(println (fib 20))

;Now the big boys:


(print "Fib Mem, 20: ") (time (fib_mem 90))
(print "Fib Matching Mem, 20: ") (time (fib_matching_mem 90))
(print "Fib Map, 20: ")(time (fib_map 90))

Thanks for the examples on destructing , Clojure code on your blog.