Introduction to Clojure

A short introduction to Clojure, the principles, syntax and some function

Transcript

1. Deon Moolman @CmdrDats Introduction to Clojure bit.ly/cljintro
2. Download Light Table http://www.lighttable.com/ bit.ly/cljintro
3. “Programming is not about typing. It’s about thinking” - Rich Hickey bit.ly/cljintro
4. The Clojure Philosophy - Michael Fogus Simplicity Empowerment Focus What is Clojure? bit.ly/cljintro
5. Functional What is Clojure? bit.ly/cljintro
6. Functional Concurrent What is Clojure? bit.ly/cljintro
7. Functional Concurrent Dynamic What is Clojure? bit.ly/cljintro
8. Functional Concurrent Dynamic Lisp What is Clojure? bit.ly/cljintro
9. Lisp Functional Concurrent Dynamic running on the JVM What is Clojure? bit.ly/cljintro
10. “By relieving the brain of all unnecessary work, a good notation sets it free to concentrate on more advanced problems.” - Alfred North Whitehead Collections Basic Syntax? bit.ly/cljintro
11. \c “string” 123 123.0 1/3 fred :name #”[0-9]+” nil true Collections Basic Syntax? bit.ly/cljintro
12. (fred bob mary) [1 2 bob] {:name “bob”, “age” 12} #{1 3 5 “mary” joe} Collections Basic Syntax? bit.ly/cljintro
13. Evaluation Reader Evaluator JVM Effect Source REPL bit.ly/cljintro
14. Switching Gears (order :spatula 200) (+ 100 (* 5 2) 5) - Some random Clojure code Basic Concepts bit.ly/cljintro
15. (def myvar 123) (def myname “Deon”) (def person {:name “Bob” :age 12}) Basic Concepts bit.ly/cljintro Vars
16. (fn [x] (+ x 10)) (def inc-ten ) #(+ % 10) Basic Concepts bit.ly/cljintro Function definitions
17. (def inc-ten ) (fn [x] (+ x 10)) (defn inc-ten [x] (+ x 10)) #(+ % 10) Basic Concepts bit.ly/cljintro Function definitions
18. (ns intro.gears (:use [clojure.tools.logging]) (:require [intro.defs :as defs]) (:import [java.util.concurrent LinkedBlockingQueue])) (info “Hello world”) (defs/inc-ten 3) (LinkedBlockingQueue.) Basic Concepts bit.ly/cljintro Namespaces
19. (def q (LinkedBlockingQueue.)) (.add q "test") (.peek q) (java.util.Calendar/getInstance) Calendar/MAY (proxy [Runnable] (run [] (println “Hello World”))) Basic Concepts bit.ly/cljintro Java interop
20. (defn add-vector [pos vector] [(+ (first pos) (first vector)) (+ (second pos) (second vector))]) (defn add-vector [[x y] [vx vy]] [(+ x vx) (+ y vy)]) (add-vector [1 2] [5 6]) => [6 7] Basic Concepts bit.ly/cljintro Destructuring
21. (defn id-name-pair [person] [(:id person) (:name person)]) (defn id-name-pair [{name :name id :id}] [id name]) (defn id-name-pair [{:keys [name id]}] [id name]) Basic Concepts bit.ly/cljintro Destructuring
22. “The four building blocks of the universe are fire, water, gravel and vinyl.” - Dave Barry Groundwork Functions bit.ly/cljintro
23. Core Groundwork Functions bit.ly/cljintro
24. if (if x 1 2) (if (account-empty? account) (send-alert) (move-money)) Groundwork Functions bit.ly/cljintro
25. if let (let [x 1, y 2] (+ x (* 64 y))) (let [person (find-person id) account (find-account person)] (:balance account)) Groundwork Functions bit.ly/cljintro
26. cond (cond (nil? name) “No name” (nil? age) “No age” :else “All fine”) if let Groundwork Functions bit.ly/cljintro
27. loop recur (loop [x 1] (if (> x 5) x (recur (inc x))) if let cond (defn sum [x xs acc] (cond (nil? x) acc :else (recur (first xs) (rest xs) (+ acc x))) Groundwork Functions bit.ly/cljintro
28. and or (and 1 5) => 5 (or 1 false) => 1 (and (old-enough? person) (qualifies? person)) (or (old-enough? person) (qualifies? person)) if let loop recur cond Groundwork Functions bit.ly/cljintro
29. apply (defn sum3 [x y z] (+ x y z)) (let [x [2 3 4]] (sum3 (nth x 0) (nth x 1) (nth x 2)) (let [x [2 3 4]] (apply sum3 x)) if let loop recur and or cond Groundwork Functions bit.ly/cljintro
30. complement (defn too-big? [x] (> x 50)) (defn small-enough? [x] (not (too-big? x))) if let loop recur and or cond apply (defn complement [f] (fn [x] ...)) Groundwork Functions bit.ly/cljintro
31. complement (defn too-big? [x] (> x 50)) (defn small-enough? [x] (not (too-big? x))) (def small-enough? (complement too-big?)) if let loop recur and or cond apply (defn complement [f] (fn [x] (not (f x)))) Groundwork Functions bit.ly/cljintro
32. if let loop recur and or cond apply complement juxt (defn id-name-pair [person] [(:id person) (:name person)]) (def id-name-pair (juxt :id :name)) (map (juxt :width :length :height) items) (defn juxt [& fs] (fn [x] ...)) Groundwork Functions bit.ly/cljintro
33. if let loop recur and or cond apply complement juxt (defn id-name-pair [person] [(:id person) (:name person)]) (def id-name-pair (juxt :id :name)) (map (juxt :width :length :height) items) (defn juxt [& fs] (fn [x] (vec (map ... fs)))) Groundwork Functions bit.ly/cljintro
34. if let loop recur and or cond apply complement juxt (defn id-name-pair [person] [(:id person) (:name person)]) (def id-name-pair (juxt :id :name)) (map (juxt :width :length :height) items) (defn juxt [& fs] (fn [x] (vec (map #(% x) fs)))) Groundwork Functions bit.ly/cljintro
35. if let loop recur and or cond apply complement juxt partial memoize fnil identity Groundwork Functions Core bit.ly/cljintro
36. Collection Groundwork Functions bit.ly/cljintro
37. conj (conj [1 2 3] 4) => [1 2 3 4] (conj ’(1 2 3) 4) => ’(4 1 2 3) (conj #{1 2 3} 4) => #{1 2 3 4} Groundwork Functions bit.ly/cljintro
38. conj assoc (assoc {:name “Deon”} :age 21) => {:name “Deon” :age 21} Groundwork Functions bit.ly/cljintro
39. conj assoc sort-by (sort-by :age [{:id 1 :age 21} {:id 2 :age 18}]) => ’({:age 18, :id 2} {:age 21, :id 1}) Groundwork Functions bit.ly/cljintro
40. conj assoc sort-by map (def xs [{:id 1 :age 21} {:id 2 :age 18}]) (map :id xs) => ’(1 2) (map #(+ 10 (:id %)) xs) => ’(11 12) Groundwork Functions bit.ly/cljintro
41. conj assoc sort-by map reduce (reduce + [1 2 3 4 5]) => 15 (defn condsum [acc x] (if (odd? x) (+ acc x) acc) (reduce condsum 0 [1 2 3 4 5]) => 9 Groundwork Functions bit.ly/cljintro
42. conj assoc sort-by map reduce filter (filter odd? [1 2 3 4 5]) => ’(1 3 5) (filter #(> 3 %) [1 2 3 4 5]) => ’(4 5) Groundwork Functions bit.ly/cljintro
43. conj assoc sort-by map reduce filter for (for [x (range 3) y (range 3 6)] (+ x y)) => ’(3 4 5 4 5 6 5 6 7) Groundwork Functions bit.ly/cljintro
44. conj assoc sort-by map reduce filter for take lazy-seq partition concat Groundwork Functions Collection bit.ly/cljintro
45. Concurrency Groundwork Functions bit.ly/cljintro
46. atom (let [a (atom 1) x @a] (swap! a + 2) (not= @a x)) Groundwork Functions bit.ly/cljintro
47. atom ref (let [r1 (ref 0), r2 (ref 100)] (dosync (alter r1 + 12) (alter r2 - 12))) Groundwork Functions bit.ly/cljintro
48. atom ref agent (def ant (agent 100)) (defn damage [health damage] (- health damage)) (send ant damage 10) (= @ant 90) Groundwork Functions bit.ly/cljintro
49. atom ref agent future promise deliver await Groundwork Functions Concurrency bit.ly/cljintro
50. Bootstrapping Time emacs Light Table CounterClockWise VimClojure Cursive Sublime Text bit.ly/cljintro Editor Options
51. Install Leiningen: http://leiningen.org/ Bootstrapping Time Install Light Table: http://www.lighttable.com/ bit.ly/cljintro Install
52. Create a new project: > lein new sugsa-prj Bootstrapping Time Add folder to workspace in LightTable Open core.clj, evaluate foo with ⌘㾑 Open Light Table console bit.ly/cljintro
53. Bootstrapping Time add (defn -main [& args] (foo 1)) add :main sugsa-prj.core to project.clj add (:gen-class) to (ns sugsa-prj.core) > lein run bit.ly/cljintro Real Project
54. Bootstrapping Time Add maven [groupid/artifactid “1.2.3”] to :dependencies vector Open project.clj bit.ly/cljintro Add Dependencies
55. Bootstrapping Time Web Dev: ring, compojure, enlive, hiccup Database: java.jdbc, monger http://www.clojure-toolbox.com/ https://clojars.org/ bit.ly/cljintro Libraries
56. Bootstrapping Time http://www.4clojure.com/ http://clojurekoans.com/ http://tryclj.com/ bit.ly/cljintro Learning #clojure on irc.freenode.net
57. Reference Material Bootstrapping Time Books: Programming Clojure, Joy of Clojure Cheatsheet: http://clojure.org/cheatsheet Videos: http://www.infoq.com/clojure/ bit.ly/cljintro
58. Thank you. #clojure.za on irc.freenode.net @CmdrDats @clj_ug_ct bit.ly/cljintro