A Taste of Clojure

Clojure is a new and upcoming programming language that is a Lisp running on JVM.

In this talk, we explore the basic of programming in Clojure.

Transcript

1. A Taste of Clojure DevCamp2010 Abhinav Sarkar
2. About Me  Working in Java/JEE professionally for last 2 years at FICO  Programming Hobbyist  Learned JavaScript, C, Perl, Java, PHP, Python, JavaScript, Java (in that order)  Currently dabbling with Functional Programming languages: Haskell, Scala and Clojure  Some personal projects on Google Code and Github 2 DevCamp2010
3. Clojure  Clojure is a dynamic programming language that targets the Java Virtual Machine.  Clojure is a dialect of Lisp.  Clojure is a compiled language.  Clojure is predominantly a functional programming language.  Clojure 1.2 was released two weeks ago 3 DevCamp2010
4. Twitter Feelings DevCamp2010 4  Shows how people on Twitter are feeling, in real-time.  Written in Clojure + Swing  120 line (core logic) + 200 lines (Swing UI)  Written in 10 hours (specifically for purpose of demo at DevCamp2010)  Uses Apache HttpClient and JFreeChart
5. Twitter Feelings: How it works DevCamp2010 5 Twitter released their Real-time Streaming API to public a month ago  Access the Twitter sample tweet stream  Find the feeling related adjectives in each tweet's status text and lookup their type (Positive, Neutral, Negative) against a list of adjectives  Keep the count of the adjective types in a sliding window of tweets  Show the statistics on the UI in pretty charts
6. Twitter Feelings DevCamp2010 6
7. Clojure DevCamp2010 7  Leiningen – the Clojure build tool  Uses Maven for dependency management and Ant for build  Project build file written in Clojure itself
8. Clojure DevCamp2010 8  Basic Clojure data structures  List  Vector  Map  Set
9. Clojure DevCamp2010 9  def: Global Bindings  defn: Functions
10. Clojure DevCamp2010 10  Sequence manipulation  map  filter  reduce
11. Clojure DevCamp2010 11  fn: functions  #(): anonymous functions  (): invoking functions
12. Clojure DevCamp2010 12  -> and ->>: macros  Macros  allow the compiler to be extended by user code  used to define syntactic constructs which would require primitives or built-in support in other languages  possible because in Lisp “code is data”
13. Clojure DevCamp2010 13  use and import
14. Clojure DevCamp2010 14  REPL READ EVAL PRINT LOOP
15. Clojure DevCamp2010 15  Java interop  .  /  doto, ..: macros
16. Clojure DevCamp2010 16  let: Local bindings  Variants:  if-let  when-let
17. Clojure DevCamp2010 17  Lazy sequences
18. Clojure DevCamp2010 18  Code written as parse tree  Uniform prefix invocation syntax
19. Clojure DevCamp2010 19  Protocols, Types and Records  defprotocol  deftype  defrecord  reify
20. Clojure DevCamp2010 20  Concurrency primitives  future  atom  agent  ref  var  Easy thread-less concurrency
21. Clojure DevCamp2010 21  Type inferencing  Type hinting
22. Clojure DevCamp2010 22  Swing in Clojure  clj-swing  miglayout  macros to rescue again
23. Clojure: Libraries DevCamp2010 23  Clojure Core API  clojure.core  clojure.inspector  clojure.java.browse  clojure.java.io  clojure.java.javadoc  clojure.java.shell  clojure.main  clojure.pprint  clojure.repl  clojure.set  clojure.stacktrace  clojure.template  clojure.test  clojure.walk  clojure.xml  clojure.zip
24. Clojure: Libraries DevCamp2010 24  Clojure Contrib API  accumulators  base64  classpath  combinatorics  command-line  complex-numbers  condition  dataflow  duck-streams  error-kit  except  gen-html-docs  generic  Graph  http  jar  java-utils  jmx  json  logging  macros  math  miglayout  mock  monads  pprint  probabilities  profile  reflect  repl-utils  seq  sql  string  swing-utils  test-is  trace  types
25. Clojure: Libraries DevCamp2010 25  Many third-party libraries  Enlive  fnparse  ClojureCheck  ClojureQL  Composure  Ring  Lancet  Cloak  Incanter  Conjure http://clojure.org/libraries#Clojure%20Libraries-3rd-party%20Clojure%20Libraries
26. Clojure: Libraries DevCamp2010 26  All Java libraries!
27. Clojure DevCamp2010 27  Packaging  As JAR  AOT: Ahead Of Time compilation  gen-class and gen-interface
28. DevCamp2010 28 That’s all folks! xkcd #297
29. DevCamp2010 29 Learn more about Clojure at http://clojure.org Check out the code at http://github.com/abhin4v/clj_twitter_feelings See the slides at http://tinyurl.com/a-taste-of-clojure Find me at abhinav@abhinavsarkar.net @abhin4v