Scala clojure techday_2011
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This document discusses functional programming languages Scala and Clojure that run on the Java Virtual Machine (JVM). It provides an overview of what functional programming is, why it is becoming more important with multi-core processors, and why developing new languages on the JVM is advantageous due to its existing investments and performance. Specific details are given about Clojure, including how it has tight integration with Java and the JVM, uses immutable collections and lazy sequences, and provides primitives for concurrency. Scala is described as a functional language that is fast, expressive, and statically typed with features like traits, pattern matching, and XML literals. The document concludes that as developers we should choose the right tools for our
![Syntax
["red" "green" "blue"] Array
{:color "blue" :length 2} Map
:color Keyword
#(even? %) Anonymous function](https://image.slidesharecdn.com/scalaclojuretechday2011-120125121725-phpapp01/85/Scala-clojure-techday_2011-44-320.jpg)
![Lazy Sequences
import java.util.HashMap;
import java.util.Map;
public class ColorMapper {
private static String[] COLORS = {"white", "blue"};
public static Map<String, String> mapLineColors(String[] values) {
Map<String, String> retVal = new HashMap<String, String>();
int i = 0;
for (String value: values) {
retVal.put(value, COLORS[i % COLORS.length]);
i++;
}
return retVal;
}
public static void main(String[] args) {
String[] values = {"Clojure", "Java", "Scala", "Visual Basic"};
System.out.println(mapLineColors(values));
}
}](https://image.slidesharecdn.com/scalaclojuretechday2011-120125121725-phpapp01/85/Scala-clojure-techday_2011-47-320.jpg)
Scala clojure techday_2011
- 2. Functional Programming on the JVM with Scala and Clojure What they are and why you should care Cristiano Breuel Thadeu Russo Advisory Software Engineer Advisory Software Engineer ([email protected]) ([email protected])
- 3. Y = λf.(λx.f (x x)) (λx.f (x x))
- 4. Y = λf.(λx.f (x x)) (λx.f (x x))
- 5. What is functional programming about?
- 6. Lambda calculus (a.k.a λ-calculus) function definition function application recursion
- 8. Referential Integrity Avoids state and mutable data Higher-Order functions: Functions can receive and return other functions Lazy Evaluation: Evaluate an expression only when necessary
- 16. FP has been around since the 1950’s Why it is becoming more important now?
- 17. FP has been around since the 1950’s Why it is becoming more important now?
- 18. FP has been around since the 1950’s Why it is becoming more important now? Why should I care?
- 20. Because of them... ... the multi-core processors
- 21. Because of them... ... the multi-core processors (also, to become a smarter developer!)
- 22. On the other side...
- 23. On the other side... The JVM is cool!
- 24. JVM -> Java Language Huge investment already on the JVM (libraries, middleware, performance, GC, remote communication, etc..) JVM executes byte-code
- 25. The question is:
- 26. The question is: Why not create new (functional) languages on top of the JVM?
- 28. (not Closure)
- 29. Clojure has...
- 30. Clojure has... ... tight integration with the JVM and Java
- 31. Clojure has... ... tight integration with the JVM and Java ... compilation for performance
- 32. Clojure has... ... tight integration with the JVM and Java ... compilation for performance ... dynamic evaluation
- 33. Clojure has... ... tight integration with the JVM and Java ... compilation for performance ... dynamic evaluation ... memory-efficient immutable collections
- 34. Clojure has... ... tight integration with the JVM and Java ... compilation for performance ... dynamic evaluation ... memory-efficient immutable collections ... lazy sequences
- 35. Clojure has... ... tight integration with the JVM and Java ... compilation for performance ... dynamic evaluation ... memory-efficient immutable collections ... lazy sequences ... primitives for concurrency (STM, agents)
- 36. Clojure is a LISP
- 37. Clojure is a LISP (Lots of (Irritating (Stupid (Parentheses))))
- 38. Clojure is a LISP (Lots of (Irritating (Stupid (Parentheses)))) a.k.a. List Processing
- 39. LISP
- 40. LISP Homoiconicity - code is data
- 41. LISP Homoiconicity - code is data Macros
- 42. LISP Homoiconicity - code is data Macros Multiple dispatch (multi-methods)
- 43. Syntax Operands Operator (arguments) (str "Hello" "World") Expression delimiters
- 44. Syntax ["red" "green" "blue"] Array {:color "blue" :length 2} Map :color Keyword #(even? %) Anonymous function
- 46. Efficient Immutable Collections
- 47. Lazy Sequences import java.util.HashMap; import java.util.Map; public class ColorMapper { private static String[] COLORS = {"white", "blue"}; public static Map<String, String> mapLineColors(String[] values) { Map<String, String> retVal = new HashMap<String, String>(); int i = 0; for (String value: values) { retVal.put(value, COLORS[i % COLORS.length]); i++; } return retVal; } public static void main(String[] args) { String[] values = {"Clojure", "Java", "Scala", "Visual Basic"}; System.out.println(mapLineColors(values)); } }
- 48. Java Integration (def now (new java.util.Date)) (def now (java.util.Date.)) (. now getTime) (doto (JFrame.) (. add (JLabel. "Hello, Clojure!")) (. pack) (. show))
- 49. sample
- 50. Scala Fast Functional Expressive Statically typed (with type inference) Concurrent
- 51. every value is an object vals / vars traits companion objects currying closures / high order functions pattern matching / case classes XML literals Lazy evaluation, and much more...
- 52. sample
- 53. To sum up...
- 55. We cannot choose our problems.... .... but we can choose our tools. It is our responsibility to figure out the “right” tool.
- 56. Even if you can't use these languages in your day job yet, learning them will make you a better programmer!
Editor's Notes
- #2: \n
- #3: Thadeu e Cristiano: Apresenta&#xE7;&#xE3;o dos palestrantes\n
- #4: Thadeu: Apenas assustar o pessoal - dizer que precisamos antes entender o combinador Y\n
- #5: Thadeu: slide apenas de passagem, sem muitos comentarios.\n
- #6: Thadeu: basicamente ler o slide.\n
- #7: Thadeu: da wikipedia: is a programming paradigm that treats computation as the evaluation of mathematical functions and avoids state and mutable data.\nenfatiza a aplicacao de funcoes ao contrario da mudanca de estado, como eh feito em linguagens interativas\n
- #8: Thadeu: Parar em visual F# - lembrar de chamar aten&#xE7;&#xE3;o para sql e spredsheets\n
- #9: Thadeu: Parar em visual F# - lembrar de chamar aten&#xE7;&#xE3;o para sql e spredsheets\n
- #10: Thadeu: Parar em visual F# - lembrar de chamar aten&#xE7;&#xE3;o para sql e spredsheets\n
- #11: Thadeu: Parar em visual F# - lembrar de chamar aten&#xE7;&#xE3;o para sql e spredsheets\n
- #12: Thadeu: Parar em visual F# - lembrar de chamar aten&#xE7;&#xE3;o para sql e spredsheets\n
- #13: Thadeu: Parar em visual F# - lembrar de chamar aten&#xE7;&#xE3;o para sql e spredsheets\n
- #14: Thadeu: intrigar a plateia - perguntar se alguem sabe e nao deixar responder - comentar que as linguagens sempre foram vistar como muito teoricas para o mundo n&#xE3;o academico\n
- #15: Thadeu: intrigar a plateia - perguntar se alguem sabe e nao deixar responder - comentar que as linguagens sempre foram vistar como muito teoricas para o mundo n&#xE3;o academico\n
- #16: Thadeu: discutir um pouco os detalhes tecnicos do impacto\n
- #17: Thadeu: discutir um pouco os detalhes tecnicos do impacto\n
- #18: Thadeu passa para Cristiano.\n
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- #40: Thadeu: Comentar cada um dos itens acima (dizer tbm q eh menos verborragica que java) - veremos exemplo\n
- #41: Thadeu: ir para o repl e fazer alguns exemplos destes caras\nval\nfunction as objects\nreduceLeft - usar as chaves e fazer o currying\n\n\nsobre a parte de lazy - comentar que nao existem lazy collections assim como em haskell ou closure, porem\nda para criar metodos que fazer conversoes de modo lazy (usando iteradores)\n
- #42: Thadeu: Converter codigo java para scala\n
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