Teaching Basic Clojure

leandro.clj

(ns luandro)

(even? 3)



(apply + (filter even? (range 20)))

(->> (range 20)
  (filter even?)
  (apply +))


(macroexpand '(-> person (get :name)))

(apply + (filter even? (range 20)))

;(def person {:name "Leandro"
;             :address {:city "Johannesburg"
;                       :street "Rooivink"}
;             :age 16})
;
;(defn greeting [person]
;  (str "Hi " (:name person) "! Welcome to " (:location person)))
;
;(greeting (assoc person :location "Boggomsbaai"))

(def test-line
  {:name "Milk"
   :qty 15
   :discount 30M
   :unit-price 23.0M})

;345 + 10M = 355M

(def test-line2
  {:name "Bread"
   :qty 2
   :unit-price 5.0M})

(def order
  {:number "SO-1234"
   :lines [test-line test-line2]})

(defn calc-line-total
  [{:as   line
    :keys [qty unit-price discount]
    :or   {discount 0M}}]
  (- (* qty unit-price) discount))

(defn calc-total [{:as order, :keys [lines]}]
  (->> lines
    (map calc-line-total)
    (apply +)))

(defn calc-tax [order]
  (* 0.15) 780M)

(defn process-order [order]
  (assoc order
    :total (calc-total order)
    :tax (calc-tax order)))

(comment
  (process-order order)

  (foo order)

  (calc-line-total (assoc test-line :discount 15M))
  (calc-line-total test-line2)

  (->> [test-line test-line2]
    (map calc-line-total)
    (apply +))

  (- 5 nil)

  (calc-total order)

  (assoc person :location "Boggomsbaai")

  ;; Operational Form:
  ;(operator op1 op2 op3 ...)

  (def my-name "Leandro")

  (str "Hi " (:name person "Petrus") "!")



  (eval (cons 'clojure.core/+ (cons 6 (rest '(+ 1 2 3)))))

  '(+ 1 2 3)

  (eval '(+ 1 2 3))

  (def foo (fn [x] x))
  (macroexpand '(defn foo [x] x))

  (foo 3456)


  "Hello world"
  :age :name

  (and true true false)

  (or true false)

  (count '[if fn def let loop do while recur . try monitor-enter monitor-exit throw catch]))