Brief intro to clojure

Brief intro to clojure

• 1.
  Introduction to
• 2.
  A bit aboutclojure ● Since 2007. Rich Hikey ● LISP - Code represented as lists ○ (+ 1 1) ○ (println (if (= 0 0)“Right” “Wrong”)) (operator operand1 operand2 ... operandn) ● Dynamically Typed, Runs on JVM
• 3.
  Setting up Clojure Java(1.6+) Leiningen (Clojure build tool, automate projects) sudo apt-get install leiningen brew install leiningen
• 4.
  REPL - Read-Eval-Print-Loop $lein repl => (println “Hello World!”) => (+ 1 3) => (import [java.util Date]) => (Date.)
• 5.
  Data types ● Lists( 1 2 3 4 5) ● Vectors [ 1 2 3 4 5] ● Maps {:a 1 :b 2 :c 3 “d” 4 :e “val”} ● Sets #{1 2 c 3 d}
• 6.
  Defining Variable andFunctions (def counties [“Nairobi”, “Kiambu”, “Nyeri”] ) (def total-number 47) (defn square[y] (* y y)) (square 2) ; => 4 ((fn [x] (* y y)) 3) ; => 4 (#(* % %) 3) ; => 9
• 7.
  Syntax Comparison myObj.doSomething(anArg); (do-something my-objan-arg)
• 8.
  Common Data StructureFunctions Clojure (conj [1 2 3] 1) ; => [1 2 3 1] (map inc [1 2 3]) ; => [2 3 4] Python x = [1 2 3] x.append(1) for i in range(len([1 2 3])): test[i] += 1
• 9.
  Common Functions Clojure (filter even?[1 2 3 4]) ; => (2 4) (sort-by count [“aaa” “bb” “c”]) ; => (“c” “bb” “aaa” ) sorted([“aaa” “bb” “c”], key=lambda x: x.count, reverse=True) Python [x for x in [1 2 3 4] if x % 2 == 0]
• 10.
  Common Functions Clojure (assoc {:a1 :b 2 :c 3} :c 4) ; => {:a 1 :b 2 :c 4} (group-by count [“aa” “bb” “c”]) ; => {1 [“c”] 2 [“bb” “aa”] } Python mydict = {“a” 1 “b” 2 “c” 3} for key in mydict.keys(): if key == “d” mydict[key] = 4 …...
• 11.
  Common Functions Clojure (println (if(= 1 1) “correct” “wrong”) ) Python if 1 == 1: print (“correct”) print (“wrong”)
• 12.
  merge empty? sorted? if-not max max-key loop doseq let when max max-key sorted-map sorted-map-by let zipmap get zero?
• 13.
  Interoperability Java (def a (ArrayList.)) (.adda 1) (.add a 2) Javascript (def a (js/Array.)) (.push a 1) (.push a 2) (.log js/console “Hello”) (.alert js/window “Alert!”)
• 14.
  Useful Resources ● Docshttps://clojuredocs.org ● The Joy of Clojure ● Clojure for the brave and true - http://www. braveclojure.com/ ● Om - A ClojureScript interface to Facebook's React. ● How to be a frontend Ninja https://github. com/om-ninja
• 15.
  References Zach Oakes -Introduction to Clojure http://oakleaf.info/intro-to-clojure.odp Clojure for the brave http://www.braveclojure.com/getting-started/ Joy of Clojure