Clojure Notest

Clojure.clj

;; http://grimoire.arrdem.com/
;;shows how to define lambda expressions in clojure
;;one form is a shortcut
(defn empty? [string]
  (every? #(Character/isWhitespace %) string))

;; this one is a little more explicit
(defn empty2? [string]
  (every? (fn [x] (Character/isWhitespace x)) string))

;; let bindings
(let [bindings*] expr*)
;;bindings are in effect for expr only.
;;example:
(defn sum-of-squares [x y]
  (let [xs (* x x)
        ys (* y y)]
     (+ xs ys)))


;;destructuring
(defn destructure-map [{name :name}]
   name)

(destructure-map {:name "Krishna", :age 30})

;; :as form keeps the original argument passed and binds it to person
(defn destructure-map-with-as[{name :name :as person}]
  (str name " is " (person :age) " years old"))


;;two examples to understand recur
(defn print-down [x]
  (let [y (do (println "Binding x to y") x)]
     (when (pos? y)
        (println "y is " y)
        (recur (dec y)))))

(defn print-down [x]
  (do
    (println "Print-down started")
    (loop [y x]
      (when (pos? y)
         (println y)
         (recur (dec y))))))
;;in the above example "print-down" only gets executed once.
;;note that recur can only be at the tail position .. so the last statement in a flow..