Delicious currying

currying.clj

; Tons of duplicated code :'(
(defn insert-l [a s l]
  (cond
   (empty? l) `()
   (= (first l) s) (cons a l)
   :else (cons (first l) (insert-l a s (rest l)))))

(defn insert-r [a s l]
  (cond
   (empty? l) `()
   (= (first l) s) (concat l [a])
   :else (cons (first l) (insert-r a s (rest l)))))

; Currying!
(defn insert-g [se]
  (fn [a s l]
    (cond
     (empty? l) `()
     (= (first l) s) (se a l)
     :else (cons (first l) ((insert-g se) a s (rest l))))))

(def insert-r (insert-g (fn [a l] (cons a l))))

(def insert-l (insert-g (fn [a l] (concat l [a]))))

; Usage
(insert-l "new" "three" `("one" "two" "three"))
; ("one" "two" "three" "new")

(insert-r "new" "three" `("one" "two" "three"))
; ("one" "two" "new" "three")