Scala for the doubters. Максим Клыга
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The document discusses the programming language Scala, emphasizing its features that blend object-oriented and functional programming. It highlights Scala's syntax and capabilities compared to Java, using various code examples to illustrate its conciseness and expressiveness. The text also touches on Scala's potential to enhance Java programming skills, referencing prominent figures in the programming community.
Scala for the doubters. Максим Клыга
- 1. Scala for the doubters Max Klyga
- 3. I
- 4. were
- 5. to
- 6. pick
- 7. a
- 8. language
- 9. to
- 10. use
- 11. today
- 12. other
- 13. than
- 14. Java,
- 15. it
- 16. would
- 17. be
- 18. Scala.”
- 20. Scala
- 21. –James Iry, “A Brief, Incomplete, and Mostly Wrong History of Programming Languages” “A
- 22. drunken
- 23. Martin
- 24. Odersky
- 25. sees
- 26. a
- 27. Reese's
- 28. Peanut
- 29. Butter
- 30. Cup
- 31. ad
- 32. featuring
- 33. somebody's
- 34. peanut
- 35. butter
- 36. getting
- 37. on
- 38. somebody
- 39. else's
- 40. chocolate
- 41. and
- 42. has
- 43. an
- 44. idea.
- 45. He
- 46. creates
- 47. Scala,
- 48. a
- 49. language
- 50. that
- 51. unifies
- 52. constructs
- 53. from
- 54. both
- 55. object
- 56. oriented
- 57. and
- 58. functional
- 59. languages.
- 60. This
- 61. pisses
- 62. off
- 63. both
- 64. groups
- 65. and
- 66. each
- 67. promptly
- 68. declares
- 69. jihad.”
- 71. Scala OOP FP
- 73. Lightweight syntax object Main extends Application { val phonebook = Map( Alice - 212-34-56, Bob - 265-43-21 ) phonebook += (Carl - 298-76-54) println(phonebook(Alice)) for (i - 1 to 10) { println(i) } } Scala
- 74. Lightweight syntax public class Person { private String firstName; private String lastName; String getFirstName() { return firstName; } void setFirstName(String firstName) { this.firstName = firstName; } String getLastName() { return lastName; } void setLastName(String lastName) { this.lastName = lastName; } int hashCode() { .... } boolean equals(Object o) { .... } } Java
- 75. Lightweight syntax case class Person(var firstName:String, var lastName:String) Scala
- 76. Lightweight syntax boolean hasUpperCase = false; for (int i = 0; i name.length(); ++i) { if (Character.isUpperCase(name.charAt(i))) { hasUpperCase = true; break; } } Java
- 77. Lightweight syntax val hasUpperCase = name.exists(_.isUpperCase) Scala
- 78. Lightweight syntax PredicateCharacter isUpperCase = new PredicateCharacter() { public Character apply(Character ch) { return Character.isUpperCase(ch); } }; boolean hasUpperCase = Iterables.any(Lists.charactersOf(name), isUpperCase); Java + Guava
- 79. Lightweight syntax PredicateCharacter isUpperCase = (ch) - Character.isUpperCase(ch); boolean hasUpperCase = Iterables.any(Lists.charactersOf(name), isUpperCase); Java 8 + Guava
- 80. Lightweight syntax boolean hasUpperCase = name.chars().anyMatch((ch) - Character.isUpperCase(ch)); Java 8
- 81. Lightweight syntax boolean hasUpperCase = name.chars().anyMatch((ch) - Character.isUpperCase(ch)); Java 8 Scala val hasUpperCase = name.exists(_.isUpperCase)
- 82. Lambdas Java 8 •Can only access final variables •Cannot mutate variables in outer scope Scala •Can access any variables •Can mutate any accessible variables
- 83. Traits Java 8 •Can define default methods in interfaces (Java 9 allows private methods) •“Diamond” inheritance is forbidden Scala •No restrictions on method implementation •Method invocation chain determined by inheritance order
- 84. Composable Everything is an expression
- 85. Composable var x:Int if (…) { x = 10 } else { x = 0 }
- 86. Composable val x = if (…) { 10 } else { 0 }
- 87. Composable var x = List[Int]() for (i - 1 to 10) { x = i :: x }
- 88. Composable var x = for (i - 1 to 10) { yield i }
- 89. Composable Everything is an expression if for while try match
- 91. Composable import com.dull.lib class Eggs { import org.cool.lib def bacon { import org.other.cool.lib … } }
- 92. Composable class Eggs { def bacon { def inner(…) { def innerer { … } … } … } }
- 93. Pattern matching abstract class ChatProtocol case class Message(userId:Int, text:String) case class Join(userId:Int, name:String) case class Leave(userId:Int) command match { case Message(id, text) = println(s${users(id)}: ${text}) case Join(id, name) = { users += (id, name) println(s${name} joined) } case Leave(id) = { println(s${users(id)} left) users -= id } }
- 94. REPL Java 9 will finally get it too
- 97. sugar
- 98. causes
- 99. cancer
- 100. of
- 101. the
- 102. semi-colons.”
- 107. Implicits • Conversions • Extension methods via Rich Interface Pattern • Remove boilerplate code
- 108. Implicits • Conversions • Extension methods via Rich Interface Pattern • Remove boilerplate code
- 109. Generic code • Partial application • Variance annotations • Implicits • Macros
- 110. With great power comes great responsibility
- 111. Sleep of reason produces monsters
- 112. Operator overloading abuse val intermediateHandler = (:/(host, port) / target ? params : identity) https://github.com/dispatch/reboot def root = jsonObj | jsonArray def jsonObj = { ~ repsep(objEntry, ,) ~ } ^^ { case vals:List[_] = JSONObject(Map(vals:_*)) } def jsonArray = [ ~ repsep(value, ,) ~ ] ^^ { case vals:List[_] = JSONArray(vals) } def objEntry = stringVal ~ (: ~ value) ^^ { case x ~ y = (x, y) } https://github.com/scala/scala-parser-combinators Unicode operators in ScalaZ: ≠ ∋ ⇏ ★ ∅
- 113. Learning Scala will make you a better Java programmer
- 114. –Paul Graham “you
- 115. could
- 116. get
- 117. smarter
- 118. programmers
- 119. to
- 120. work
- 121. on
- 122. a
- 123. Python
- 124. project
- 125. than
- 126. you
- 127. could
- 128. to
- 129. work
- 130. on
- 131. a
- 132. Java
- 133. project.”
- 135. The Python Paradox
- 136. The Scala Paradox
- 138. Java ❤ Scala
- 139. Java ❤ Scala • Scala Maven plugin - http://davidb.github.io/scala- maven-plugin/