gistfile1.clj

(defn foldl
  [f init xs]
  (println xs)
  (cond (empty? xs) (f)
        (nil? init) (recur (partial f (first xs)) nil (rest xs))
        :else (recur (partial f init (first xs)) nil (rest xs))))

(foldl + 0 (range 10))
(0 1 2 3 4 5 6 7 8 9)
(1 2 3 4 5 6 7 8 9)
(2 3 4 5 6 7 8 9)
(3 4 5 6 7 8 9)
(4 5 6 7 8 9)
(5 6 7 8 9)
(6 7 8 9)
(7 8 9)
(8 9)
(9)
()
45

(defn foldr
  [f init xs]
  (println xs)
  (cond (empty? xs) (f init)
        :else (recur (partial f (last xs)) init (butlast xs))))

(foldr + 0 (range 10))
(0 1 2 3 4 5 6 7 8 9)
(0 1 2 3 4 5 6 7 8)
(0 1 2 3 4 5 6 7)
(0 1 2 3 4 5 6)
(0 1 2 3 4 5)
(0 1 2 3 4)
(0 1 2 3)
(0 1 2)
(0 1)
(0)
nil
45

(defn unfoldl
  [f seed]
  (cons seed (lazy-seq (unfoldl f (f seed)))))

(take 10 (unfoldl inc 0))
0
(1
0 2
1 3
2 4
3 5
4 6
5 7
6 8
7 9
8 9)
(0 1 2 3 4 5 6 7 8 9)