?4ׁB!בCט { {u 7cassandra://TgacbbJ8xnwXHIHagZ4zh8adtA_mkvitAHzSL3y3LA4 E` 7cassandra://9klVRoyrg9PQY011V1Ju4HOFbPsBaJkCvTlYOxgQssM`j 7cassandra://MMj0P_OExCs1vpvNguw8XlR5140oVHifW4LBA4Xo22AKH͠ Up.7`ט {u נ Up.7e g6.9ׁHmailto:mj@ative.dkׁ ׁ ЈE Up.7aE dClojure in 10 Minutes
Clojure Meet-Up Copenhagen
September 23, 2010
Martin Jul, mj@ative.dk / @mjul
7cassandra://9klVRoyrg9PQY011V1Ju4HOFbPsBaJkCvTlYOxgQssM`j Up.7b Up.7a
בCט {u 7cassandra://kEH8badYPSwzXIv7vP8H2unrvu53C3VZmC5hlxUskhU ` 7cassandra://9U48ovZBHDpXC1de06jifvQ0340d-YnJK4yAxTHkaOs$` j 7cassandra://fZxyOmXm4jBDyPqoArA8Hiq46m1pXXzQ8dRr7uVAbqE0j|͠ Up.7fט { {u 7cassandra://M7VusItWP7sdUnQ8AhtiIT2lMEmwRh1L3uloYTHeLB8 t` 7cassandra://rnukfHtTOywGIPPogrk8qq_6UQRKL3L7VdmVx5JIU44$` j 7cassandra://HLjo3CmmCNVCvOB6hSqNtlILkP-8eIZ6FhlMsmo6HMMC|͠ Up/7gנ Up/7l e@9ׁHhttp://core.clׁ ׁ ЈEWhat is Clojure?
• Lisp
• Functional Programming
• Immutable, persistent data structures
• Software Transactional Memory
• Object-oriented (sort of)
• Macros
• Managed code: JVM and CLR
Clojure is the future!
-- Uncle Bob
Getting off the
Lisp Island
7cassandra://9U48ovZBHDpXC1de06jifvQ0340d-YnJK4yAxTHkaOs$` j Up/7hESyntax and Data Types
; This is a comment, semicolon is similar to // in C# / Java
;; List is the most common data structure
'(1 2 3)
;; Vector is a list that is indexable by position
[1 2 3]
;; Maps are associative data structures
{:key "value", :id 42}
;; Sets are mathematical sets
#{1 2 3}
;; Expressions are lists of form (function arg-1 arg-2 ...)
(println "Hello, World")
(+ 1 2 3)
file: core.clj
List
Vector
Map
Set
Expression
7cassandra://rnukfHtTOywGIPPogrk8qq_6UQRKL3L7VdmVx5JIU44$` j Up/7i Up/7h
בCט {u 7cassandra://8aTxLyTNlT8ThC-qaR3ZlpN5mPv8HeXG1rWrpTkv9H0 C` 7cassandra://5TQnpp8RKxqXJnuPA7yL7h5EsrGcYudiVkEWZE1WGMUu`j 7cassandra://S2IHpebEyhriQcxY4IVIlgYtSKZ2hu96QpkxiXiu5cYR)͠ Up/7mט { {u 7cassandra://2jlnGxDIhrp_5M-dW1XtzJ9BlbdBr9oWa98lmItRYkI e` 7cassandra://ZeNReWAf2tSngZLzQhk_N2nFErniVv2bOKIi2xXopIg `j 7cassandra://8hCtmskUvjHESjhFJwY0vAtYEJpH3-KvvyRXKRiVbxcf͠ Up/7nנ Up/7t ez9ׁHhttp://functional.clׁ ׁ ЈE bClojure Basics
file: functional.clj
Incidentally this could also have
been a modem connect string
7cassandra://5TQnpp8RKxqXJnuPA7yL7h5EsrGcYudiVkEWZE1WGMUu`j Up/7oE ,Functional Programming
file: functional.clj
7cassandra://ZeNReWAf2tSngZLzQhk_N2nFErniVv2bOKIi2xXopIg `j Up/7p Up/7o
בCט {u 7cassandra://d4AxTepZn-WLfti59mfWyJt8ekXkIWBsd0G2SOpeFf8 ?` 7cassandra://Gn-5a4nUyvmev1HM_j1hMtwb8ExiPnz7RUh2bOW1DmM*` j 7cassandra://QjnlZAGIevRcFHfbphvRjoEZIwaj_DJwLRdAaKFQIQA\ F͠ Up/7uט { {u 7cassandra://RBdmyKtamX-Mz84At5Z_hKiLPkxPBdugXc7MIopyff0 h` 7cassandra://c4p7plM0btjZaFjjcfUZmAzIRy0w5AW8Jhd7Hae2GnM `j 7cassandra://acKSjeZOV5IjbPJcNpmvtqGBiYyxSa7ivBGbzt1EkqU4͠ Up/7vE Simple and Concise
(defn blank? [s]
(every? #(Character/isWhitespace %) s))
Source: Programming Clojure by Stuart Halloway (Pragmatic Programmers, 2009)
7cassandra://Gn-5a4nUyvmev1HM_j1hMtwb8ExiPnz7RUh2bOW1DmM*` j Up/7wE ”State – you’re doing it wrong”
• Immutable
• Persistent (struktural sharing, not copying)
b
(def a (list 1 2 3))
(def b (rest a))
a
1
• Simpler code
• Less concurrency issues
2
3
e.g. stable
enumerations
7cassandra://c4p7plM0btjZaFjjcfUZmAzIRy0w5AW8Jhd7Hae2GnM `j Up/7x Up/7w
בCט {u 7cassandra://DgOaIzmLLTZ46UtbUDcnfjWfDoj5eObgQhcnaJ0Xg1s "` 7cassandra://YYDBhrc4RvYd5Ymj8XP9BkfNrwkB27W_o6U0yTdhAVI*(`j 7cassandra://HsLWv3E18QxA2uW596qihdY9yViOo4i2XU_vzapXdDÍc ͠ Up/7{ט { {u 7cassandra://g5EqSV7TngEmiAPC3c-McIHI3AxNiWrt9ejFh30j64o ` 7cassandra://6Hvkg53VCg4lPIqbFkM4tfO1dphNg1clSNJrqXhdqkI)`j 7cassandra://H55lTJU47BH8-fi9_9BCm5XNNiafn1lBMLrIdfpAXG4͡b͠ Up/7|נ Up/7
e09ׁHhttp://oo.clׁ ׁ ЈE gSTM – Software Transactional Memory
ref
1
1
2
file: stm.clj
concurrency-safe
in-memory
transactions!
7cassandra://YYDBhrc4RvYd5Ymj8XP9BkfNrwkB27W_o6U0yTdhAVI*(`j Up/7}E QObject Oriented with Protocols
(price-with-vat espresso)
(vat iver)
file: oo.clj
7cassandra://6Hvkg53VCg4lPIqbFkM4tfO1dphNg1clSNJrqXhdqkI)`j Up/7~ Up/7}
בCט {u 7cassandra://ZVbATw4wYk_-BY2otW13hgD9VE64nF2RCISf66aVi1c i` 7cassandra://wPvRop_n5b6LQNnUqKqdjjOXhUUaE3FZwCo0WLEMZcw"`j 7cassandra://qm3Z5kcYKK3siRpSr36oHUAAzCWnLKjP5hO64Krt_CI͖͠ Up07ט { {u 7cassandra://PDbZAcoJ0nGLQmW0ACTQzgcduBmjPEnm1AEbvU_WeqA ` 7cassandra://2Uxw7JR9brTizysOzV1XFgxgM_TvK1xiVs1PMSZIkbE&`j 7cassandra://pbBQhq3yTJDrglqk8Txfrl-iDNvsdPYHyt5Cvijla2Q0Ef͠ Up07נ Up07 yeI9ׁHhttp://multi.clׁ ׁ ЈE ;Multi-methods
Not your mother’s
dispatch
file: multi.clj
7cassandra://wPvRop_n5b6LQNnUqKqdjjOXhUUaE3FZwCo0WLEMZcw"`j Up07E The Clojure Compiler
Text
Clojure data structures
(read stream)
Reader
AST
Macro
evaluation
(eval ast)
Compiler is
available at
runtime
Byte
code
AST
Compiler
Your hip friends call this
language homoiconic
Great for DSLs
7cassandra://2Uxw7JR9brTizysOzV1XFgxgM_TvK1xiVs1PMSZIkbE&`j Up07 Up07
בCט {u 7cassandra://o5kwaNPGg7jtPnH3siOqLhlC9hkOXDLdO39VZdaoWnk Yy` 7cassandra://nW-Ww6Fb0X3kHeYGR57nKljrjYIzOrG_4jaw0SG-os8"` j 7cassandra://uGjCH_h7Rn-_fHnz0WEkTy1oq-Zr5x45jbEfj8X2oII4|͠ Up17נ Up17 {dG9ׁHhttp://web.coׁ ׁ Јנ Up17 f9ׁH 'http://github.com/weavejester/compojureׁ ׁ Јנ Up17 ہ 9ׁHhttp://compojure.roׁ ׁ Јנ Up17 gV9ׁHhttp://ring.adapter.jeׁ ׁ Јנ Up17 =
9ׁHhttp://compojure.coׁ ׁ ЈEXExample: Compojure web app
(ns hello-world
(:use compojure.core, ring.adapter.jetty)
(:require [compojure.route :as route]))
(defroutes main-routes
(GET "/" [] "Hello World
")
(route/not-found "Page not found
"))
(run-jetty main-routes {:port 8080})
Source: http://github.com/weavejester/compojure
shorter than your
web.config!
7cassandra://nW-Ww6Fb0X3kHeYGR57nKljrjYIzOrG_4jaw0SG-os8"` j Up17E Up17 Up17
,Clojure in 10 minutess !Doh dit is de description Ui{.͵