Clojure introduction, concepts, functional programming elements. Real world usage. Clojure community heros.

1. 我把所有穿过的袜子在沙发上摆成一个二叉堆，每天回家便把袜子脱下来放在堆的最末尾，然后每次拿起两双袜子放在鼻子下闻闻，不断向上调整它在堆中的位置，直到比它的父亲更臭为止。这样，我每天早晨出门时便能方便地选出一双最不臭的袜子。

2. Clojure Practical Functional Approach on JVM Sun Ning 2011.11.28

4. Real World Clojure

5. Clojure People

8. Lisp Syntax

9. State Management

10. Macro

11. Java Interop

13. Lisp Syntax

14. State Management

15. Macro

16. Java Interop

18. Functions as First-Class Values

19. Lambdas and Closures

20. Higher-Order Functions

21. Side-Effect-Free Functions

22. Recursion

23. Lazy vs. Eager Evaluation

24. Declarative vs. Imperative Programming

26. Persistent data structure zs = xs + ys

28. Lambdas and Closures

29. Higher-Order Functions ;; integer as first class value (def a 10) ;; function as first class value (def b (fn [x] (+ x a))) ;; anonymous function #(+ a %) ;; function that generate a closure (def c (fn [x] #(+ x %))) ;; high order function (function as parameter) (def d (fn [f x] (f x a)))

35. Lisp Syntax

36. State Management

37. Macro

38. Java Interop

40. Character:

41. Integer: 1 2 3

42. String: “hello”

43. Keyword: :world

44. Boolean: true

45. Null: nil

47. List: (1 2 3)

48. Set: #{1 2 3}

49. Map: {:a 1 :b 2}

51. (def b “tomcat”)

52. (def c (fn [x y] (+ x y)))

53. (def c #(+ %1 %2))

54. (defn c [x y] (+ x y))

56. Lisp Syntax

57. State Management

58. Macro

59. Java Interop

62. Atom – Synchronous, Independent

63. Agent – Asynchronous

64. Vars – Thread local values

65. State management ;;refs and STM (def a (ref 0)) (def b (ref 1)) (dosync (alter a inc) (alter b + @a)) @a @b ;;atoms (def a (atom 0)) (def b (atom 1)) (swap! a inc) (swap! b + @a) @a @b ;;agents (def a (agent 0)) (def b (agent 1)) (send a inc) (send b + @a) ;;thread local binding (def a 0) (def b 1) (binding [a 100] (+ b a)) a

67. Each transaction merrily chugs along making changes to in-transaction values only.

68. Examine the refs against the modification target for conflicts.

69. Commit changes or Retry

71. Lisp Syntax

72. State Management

73. Macro

74. Java Interop

76. Macro (defmacro cd "change current directory" [path & cmd] `(str "cd " ~path "; " ~ @cmd) ) (defmacro run "simply run a command" [cmd] `(str ~cmd "; ") )

77. Macro (cd “/home/nsun” (run “rm -rf ./*”)) cd /home/nsun; rm -rf ./*; (macroexpand '(cd "/home/nsum" (run "rm -rf ./*"))) (clojure.core/str "cd " "/home/nsum" "; " (run "rm -rf ./*"))

79. Lisp Syntax

80. State Management

81. Macro

82. Java Interop

83. Java Interop – Java for Clojure (import java.util.Date) (def now (Date.)) (.getTime now) (System/currentTimeMillis)

84. Java Interop - Clojure->Java (ns gen-class-test.core (:gen-class :state value :init init :constructors {[String] []} :methods [[printValue [String] void] ^{:static true} [version [] String]])) (defn version [] "1.0") (defn -init [name] [[] (atom {:name name})]) (defn -printValue [this prefix] (println (str prefix @(.value this))))

85. Real World Clojure where functional programming landed

87. Web development

88. Databases

90. Lamina – Abstraction of Queue

91. Gloss – Abstraction of bytes protocol

92. Based on Netty

93. Aleph (defcodec dummy-codec (finite-frame :int24 (string :utf8))) (defn echo-handler [ch client-info] (receive-all ch #(do (println %) (enqueue ch %)))) (start-tcp-server echo-handler {:port 1234, :frame dummy-codec}) Gloss codec Lamina queue Aleph

95. Noir

96. Ring (defn app [req] {:status 200 :headers {"Content-Type" "text/html"} :body "Hello World from Ring"}) Middleware Middleware Middleware Handler Middleware

97. Compojure framework (defroutes default-routes (GET "/rage/:id" [] get-rage) (GET "/rages/:channel" [] get-rages)) (defn get-rage [req] (let [id (:id (:params req))] (json-response (get-data id)))) (defroutes default-routes (GET "/rage/:id" [] get-rage) (GET "/rages/:channel" [] get-rages))

98. Clojure JDBC DDL ;; database config (def db {:classname "org.hsqldb.jdbc.JDBCDriver" :subprotocol "hsqldb" :subname "testdb" :user "SA" :password ""}) (defn create-db [] (jdbc/with-connection db (jdbc/create-table table-name [:name "VARCHAR(32)" "PRIMARY KEY"] [:submitter "VARCHAR(32)"] [:title "VARCHAR(512)"])))

99. Clojure JDBC DML (jdbc/with-connection db (jdbc/with-query-results results [(str "select * from " (name table-name))] (into [] results)))

100. Clojure People Meet clojure hackers on github

103. Hammock-driven-development

105. Author of “The Joy of Clojure”

106. http://blog.fogus.me/

109. Cascalog (clojure query language on hadoop)

111. Author of Ring spec

113. Clj-http

114. Clj-stacktrace

115. ...

122. @ibdknox (Noir, Korma, I Will Build Your Prototype )

123. @weavejester (Compojure, Ring)

124. @ghoseb (Planet Clojure)

125. @cemerick (O'Reilly Clojure Programming)

126. @stuarthalloway (Pragmatic Programming Clojure)

127. @stuartsierra (Clojure core developer, Apress Practical Clojure)

128. Q&A

129. Thanks