![Clojure的数据类型Integer –123456789Double 1.234BigDecimal 1.234mRatios(分数)22/7Strings “hello”Characters \a \b \cSymbols foo barKeywords :foo :barBooleans true falseNull nilRegex patterns #“[a-z]*\d+”2010-08-10淘宝内部分享-伯岩7](https://image.slidesharecdn.com/clojure-100817050310-phpapp01/85/Clojure-7-320.jpg)
![数据结构List单向链表(1 2 3 4 5) (list \a \b\ c)\Vector类似数组，索引访问[1 2 3 4 5] [foo bar]Map key/value{:a 1 :b 2} {1 “hello” 2 “world”}Set集合，不能重复#{foo bar}全部可嵌套2010-08-10淘宝内部分享-伯岩8](https://image.slidesharecdn.com/clojure-100817050310-phpapp01/85/Clojure-8-320.jpg)
![Symbols可以理解成变量，绑定特定的值user=> a java.lang.Exception: Unable to resolve symbol: a in this context (NO_SOURCE_FILE:0)user=> (def a 1) #'user/a user=> a 1user=> (let [a 1] a) 1user=> (binding [a 2] a) 22010-08-10淘宝内部分享-伯岩12](https://image.slidesharecdn.com/clojure-100817050310-phpapp01/85/Clojure-12-320.jpg)
![let和bindinglet是用词法作用域的不可变值“遮蔽”了外部的symbol绑定值。Binding则是创建thread-local级别的symbol绑定值。例子：(def foo 1)(defn print-foo [] (println foo))(let [foo 2] (print-foo)) =>1(binding [foo 2] (print-foo)) =>22010-08-10淘宝内部分享-伯岩13](https://image.slidesharecdn.com/clojure-100817050310-phpapp01/85/Clojure-13-320.jpg)
![Special forms(def name init-value?) 定义全局变量(if test then-expr else-expr)条件语句(quote form)返回不会被执行的form(fn name? ([params* ] exprs*)+)定义函数其他：let loop recur do new . throw try set! var14](https://image.slidesharecdn.com/clojure-100817050310-phpapp01/85/Clojure-14-320.jpg)
![Macro——宏Macro是Clojure元编程的主要方式什么是Macro?模板语言C语言的预处理器unless:(defmacro unless [test expr] `(if ~test nil ~expr)) (if ${test} nil ${expr})15](https://image.slidesharecdn.com/clojure-100817050310-phpapp01/85/Clojure-15-320.jpg)
![函数Clojure是FP——函数式编程语言函数是First-Class Values作为参数作为返回值保存为变量(def square (fn [x] (* x x))) (squre 3) => 9 (defn square [x] (* x x))17](https://image.slidesharecdn.com/clojure-100817050310-phpapp01/85/Clojure-17-320.jpg)
![Sequence(2)(iterate inc 0)自然数集合(use ‘[clojure.contrib.lazy-seqs :only(primes)]) (def ordinals-and-primes (map vector (iterate inc 1) primes))[1 2] [2 3] [3 5]…[n nth-primes]的vector集合延迟和无穷doall dorun 强制seq的副作用触发23](https://image.slidesharecdn.com/clojure-100817050310-phpapp01/85/Clojure-23-320.jpg)
![Sequence(3)(first (System/getProperties))#<Entry java.runtime.name=OpenJDK Runtime Environment>(rest (.getBytes “hello”))(101 108 108 111)(sort (re-seq #“\w+” “the quick brown fox”))(“brown” “fox” “quick” “the”)(count (file-seq (File. ".")))(with-open [rdr (reader “hello.clj”)] (count (line-seq rdr)))TODO(xml-seq)24](https://image.slidesharecdn.com/clojure-100817050310-phpapp01/85/Clojure-24-320.jpg)
![Clojure的实现——调用函数调用就是Java的方法调用没有额外的类型系统和转换没有额外的参数对Java的调用：直接调用 or 反射没有包装、捕获异常和动态转换Type hints和类型推断允许直接调用(def class-name [^Class c] (.getName c))*warn-on-reflection* 提示反射，避免反射39](https://image.slidesharecdn.com/clojure-100817050310-phpapp01/85/Clojure-39-320.jpg)
Clojure的魅力
- 3. What is clojure?A dynamic programming language for JVMClojure is a LispClojure is functionalSupporting ConcurrencyDesigned for the JVMHistory3 years in development,released 10/2007Authror: Rich HickeyHomepage: http://clojure.org3
- 4. Clojure is a LispClojure是Lisp的一种方言，就像scheme、common lisp也是Lisp的方言一样。Clojure同样也是Homoiconicity(同像性)Homoiconicity:编程语言的一种属性，是指该语言的基本表现形式本身同时也是该语言自身的数据结构。Homoiconicity使得元编程更容易Code vs. Data小核心Sequences抽象宏(macro)非OO模型4
- 5. Hello WorldREPL——交互式编程环境user=> (println "hello world") hello world nil5
- 6. Code vs. Data从代码角度 (println "hello world")函数 参数 从数据角度 (println "hello world")一个list6
- 7. Clojure的数据类型Integer –123456789Double 1.234BigDecimal 1.234mRatios(分数)22/7Strings “hello”Characters \a \b \cSymbols foo barKeywords :foo :barBooleans true falseNull nilRegex patterns #“[a-z]*\d+”2010-08-10淘宝内部分享-伯岩7
- 8. 数据结构List单向链表(1 2 3 4 5) (list \a \b\ c)\Vector类似数组，索引访问[1 2 3 4 5] [foo bar]Map key/value{:a 1 :b 2} {1 “hello” 2 “world”}Set集合，不能重复#{foo bar}全部可嵌套2010-08-10淘宝内部分享-伯岩8
- 9. 语法前缀运算符(+ 1 2 3) (println (str “hello “ “world”))(op …), op可以为少数几个special formMacro返回函数的表达式数据结构即代码语法 == 数据结构的解释9
- 12. Symbols可以理解成变量，绑定特定的值user=> a java.lang.Exception: Unable to resolve symbol: a in this context (NO_SOURCE_FILE:0)user=> (def a 1) #'user/a user=> a 1user=> (let [a 1] a) 1user=> (binding [a 2] a) 22010-08-10淘宝内部分享-伯岩12
- 13. let和bindinglet是用词法作用域的不可变值“遮蔽”了外部的symbol绑定值。Binding则是创建thread-local级别的symbol绑定值。例子：(def foo 1)(defn print-foo [] (println foo))(let [foo 2] (print-foo)) =>1(binding [foo 2] (print-foo)) =>22010-08-10淘宝内部分享-伯岩13
- 14. Special forms(def name init-value?) 定义全局变量(if test then-expr else-expr)条件语句(quote form)返回不会被执行的form(fn name? ([params* ] exprs*)+)定义函数其他：let loop recur do new . throw try set! var14
- 15. Macro——宏Macro是Clojure元编程的主要方式什么是Macro?模板语言C语言的预处理器unless:(defmacro unless [test expr] `(if ~test nil ~expr)) (if ${test} nil ${expr})15
- 16. Macro`Syntax quote 标记为模板~Unquote 替代value~@Splicing unquote 拼接list的内容foo# Auto-gensym 创建唯一符号名称16
- 17. 函数Clojure是FP——函数式编程语言函数是First-Class Values作为参数作为返回值保存为变量(def square (fn [x] (* x x))) (squre 3) => 9 (defn square [x] (* x x))17
- 18. 高阶函数18
- 20. 语法小结20
- 21. Sequences传统Lisp中list的抽象(cons item seq)将item插入seq的首部创建新的seq(seq coll)如果集合为空，返回nil，否则返回集合的seq(first seq) == (car list)返回seq的第一个元素(rest seq) == (cdr list)返回seq除第一个元素之外的元组，如果没有则为nil21
- 22. Sequence(1)22
- 23. Sequence(2)(iterate inc 0)自然数集合(use ‘[clojure.contrib.lazy-seqs :only(primes)]) (def ordinals-and-primes (map vector (iterate inc 1) primes))[1 2] [2 3] [3 5]…[n nth-primes]的vector集合延迟和无穷doall dorun 强制seq的副作用触发23
- 24. Sequence(3)(first (System/getProperties))#<Entry java.runtime.name=OpenJDK Runtime Environment>(rest (.getBytes “hello”))(101 108 108 111)(sort (re-seq #“\w+” “the quick brown fox”))(“brown” “fox” “quick” “the”)(count (file-seq (File. ".")))(with-open [rdr (reader “hello.clj”)] (count (line-seq rdr)))TODO(xml-seq)24
- 25. Java InteropsClojue Strings == Java StringsClojure Numbers == Java NumbersClojure Collections实现java Collection接口Clojure函数实现Runnable和Callable接口Clojure可以继承和实现Java的类和接口Clojure的seq库可以直接使用在Java的String和Array以及Iterable25
- 26. Java Interops实例(. Math PI) Math/PI(new java.util.Date) (java.util.Date.)(. date getYear)(.getYear date)(.. System getProperties (get “java.version”))(doto (JFrame.) (add (Jlabel. “hello world”)) pack show)(int-array 3)(aset a 0 1) (aget a 0) (alength a)26
- 27. Persistent Data StructuresClojure的数据结构都是immutable的每次更新都将创建一个新的数据结构复制的开销解决方案：结构共享，Persistent数据结构Git的tree结构Couch DB的索引Clojure的数据结构27
- 34. Ref和事务(def songs (ref #{}))创建ref@songs取ref的值(dosync (refset songs #{“dangerous”}))改变ref指向的值，需要包装在事务里(def singers (ref #{})) (dosync (ref-set sings #{“dangerous”}) (ref-set singers #{“MJ”}))协作更新多个ref(dosync (alter songs conj “heal the world”))查询并更新(dosync (commute songs conj “heal the world”))更新操作是可交换的，符合交换律34
- 36. Atomic管理独立的可变状态，类似Java的AtomicReference(内部实现）(def mem (atom {}))创建atom@meme取值(reset! mem {:a 1})设值，无需事务(swap! mem assoc :b 2)查询并更新(compare-and-set! mem oldValue newValue)原子的比较更新适合实现缓存 memoize36
- 37. Agent用于异步的状态更新(def counter (agent 0))创建agent@counter取值(send counter inc)发送任务，适合非阻塞任务(send-off counter inc)发送任务，适合阻塞型任务，如IO操作(await counter)等待任务结束每个agent每次只执行一个任务，同一个线程发送的任务有序可以在事务中使用，那么当且仅当事务commit成功的时候发送任务 实现bin log37
- 39. Clojure的实现——调用函数调用就是Java的方法调用没有额外的类型系统和转换没有额外的参数对Java的调用：直接调用 or 反射没有包装、捕获异常和动态转换Type hints和类型推断允许直接调用(def class-name [^Class c] (.getName c))*warn-on-reflection* 提示反射，避免反射39
- 40. Clojure的实现——STMMVCC——Multiversion Concurrency Control每个ref维持一张版本列表事务开始和提交的时候都分配一个时间戳提交成功的时候，将commit时间戳和新的值加入Ref的版本列表Write Conflictabort and retryBargeCommute，不做写冲突检查，不取得ref的ownership，计算立即可见，但是在commit的时候如果发现ref值被其他事务更改了，重新运行计算。Software Transactional Memory40
- 42. 没有谈到的……函数的递归调用let/fn/loop的destructuring列表推断(Lisp comprehesions)关系集合代数Multimethods并行计算(pmap pvalues pcalls)……2004-5-31淘宝内部分享-烟客42