はじめての関数型プログラミング教室

書いて遊ぼうScalaハンズオン

Transcript

1. ͸͡Ίͯͷؔ਺ܕ
   ϓϩάϥϛϯάڭࣨ
   Hands-on Functional Programming in Scala
   

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2. ຊ೔࿩͢͜ͱ
   • ײ֮తʹཧղ͢Δؔ਺ܕϓϩάϥϛϯά
   • ίϨΫγϣϯͷ͜ͱ
   • ύλʔϯϚονͷ͜ͱ
   • ࠶ؼͷ͜ͱ
   

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3. ຊ೔࿩͞ͳ͍͜ͱ
   • Scalaͷ࣮༻తͳจ๏
   • Ϋϩʔδϟ
   • ෦෼ద༻
   • ΧϦʔԽ
   • ϞφυͳͲ
   

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4. ScalaΛಈ͔͢·Ͱ
   

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5. Mac OSΛ͓࢖͍ͷํ
   XCodeΛΠϯετʔϧ
   Command Line Developer ToolsΛΠϯετʔϧ
   $ xcode-select —install
   XCodeͷϥΠηϯεʹಉҙ
   $ sudo xcodebuild -license
   HomebrewΠϯετʔϧ
   $ ruby -e "$(curl -fsSL https://raw.githubusercontent.com
   /Homebrew/install/master/install)”
   ScalaΠϯετʔϧ
   $ brew install scala
   

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6. Mac OSΛ͓࢖͍ͷํ
   XCodeΛΠϯετʔϧ
   Command Line Developer ToolsΛΠϯετʔϧ
   $ xcode-select —install
   XCodeͷϥΠηϯεʹಉҙ
   $ sudo xcodebuild -license
   HomebrewΠϯετʔϧ
   $ ruby -e "$(curl -fsSL https://raw.githubusercontent.com
   /Homebrew/install/master/install)”
   ScalaΠϯετʔϧ
   $ brew install scala ͜Ε͚ͩ
   

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7. WindowsΛ͓࢖͍ͷํ
   • JDKΠϯετʔϧʢJava SEʣ

   http://www.oracle.com/technetwork/jp/java/javase/downloads/index.html
   • ScalaΠϯετʔϧ

   http://www.scala-lang.org/download/
   • ؀ڥม਺Λઃఆ

   ίϯτϩʔϧύωϧʼγεςϜʼγεςϜͷৄࡉઃఆ

   Ϣʔβʔఆٛ؀ڥม਺ʹ৽ن௥Ճʢ໊લ͸PATHʹઃఆʣ

   JDKΛΠϯετʔϧͨ͠ϑΥϧμԼbin·Ͱͷύε;ʢʀͰ۠੾Δʣ

   ScalaΛΠϯετʔϧͨ͠ϑΥϧμԼͷbin·Ͱͷύε
   

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8. ؀ڥߏங͕໘౗͍͘͞ํ
   • ΦϯϥΠϯͷScala࣮ߦ؀ڥ͕͋Γ·͢
   • tutorialspoint.com
   • paiza.io
   • codebunk.com
   • scastie.org
   

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9. ศརͳπʔϧ
   

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10. “Hello Scala!”
    

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11. REPL
    $ scala
    Welcome to Scala version 2.11.2 (Java HotSpot(TM) 64-Bit Server VM,
    Java 1.8.0_25).
    Type in expressions to have them evaluated.
    Type :help for more information.
    scala> println("Hello Scala!")
    Hello Scala!
    scala> :quit
    

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12. REPL
    $ scala
    Welcome to Scala version 2.11.2 (Java HotSpot(TM) 64-Bit Server VM,
    Java 1.8.0_25).
    Type in expressions to have them evaluated.
    Type :help for more information.
    scala> println("Hello Scala!")
    Hello Scala!
    scala> :quit
    λʔϛφϧ͔Β”scala”ίϚϯυΛ࣮ߦ
    

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13. REPL
    $ scala
    Welcome to Scala version 2.11.2 (Java HotSpot(TM) 64-Bit Server VM,
    Java 1.8.0_25).
    Type in expressions to have them evaluated.
    Type :help for more information.
    scala> println("Hello Scala!")
    Hello Scala!
    scala> :quit
    λʔϛφϧ͔Β”scala”ίϚϯυΛ࣮ߦ
    ऴྃ͢Δͱ͖͸”:quit”΋͘͠͸”:q”
    

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14. IDE
    object Main {
    def main(args: Array[String]) {
    println("Hello, Scala!")
    }
    }
    

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15. IDE
    object Main {
    def main(args: Array[String]) {
    println("Hello, Scala!")
    }
    }
    ͓·͡ͳ͍
    

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16. IDE
    object Main {
    def main(args: Array[String]) {
    println("Hello, Scala!")
    def hello(lang:String = "World"): String =
    "Hello, %s!".format(lang)
    println(hello("Scala"))
    }
    }
    ͓·͡ͳ͍
    ͜Μͳ͔Μ͡ͰॲཧΛॻ͍͍͖ͯ·͢
    

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17. 15෼ͰֶͿ Scala
    

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18. ຊ೔ͷScalaจ๏͓͠ͳ͕͖
    • ग़ྗ
    • ม਺
    • ؔ਺Ϧςϥϧ
    • ίϨΫγϣϯ
    • ύλʔϯϚον
    

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19. ຊ೔ͷScalaจ๏͓͠ͳ͕͖
    • ग़ྗ
    • ม਺
    • ؔ਺Ϧςϥϧ
    • ίϨΫγϣϯ
    • ύλʔϯϚον
    ࠓ೔͸͜Ε͚ͩ
    

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20. Scalaͷ͍͍ͱ͜Ζ
    • ܕਪ࿦ (Type Inference)
    • ϓϨʔεϗϧμʔ
    • ౶ҥߏจ (Syntactic sugar)
    • ڧྗͳύλʔϯϚον
    • ҉໧ͷܕม׵ (Implicit Conversions)
    

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21. ScalaٯҾ͖Ϩγϐ
    ஛ఴ௚थʗౡຊଟՄࢠ ஶ
    

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22. ScalaٯҾ͖Ϩγϐ
    ஛ఴ௚थʗౡຊଟՄࢠ ஶ
    ৄ͘͠͸ͪ͜Β
    

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23. Scala ΫϨυ
    • var ېࢭ
    • mutable ېࢭ
    • while/for ϧʔϓ ېࢭ
    • null ېࢭ
    • Option.get ېࢭ
    • return ېࢭ
    • if ېࢭ (൒෼৑ஊ)
    

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24. Scala ΫϨυ
    • var ېࢭ
    • mutable ېࢭ
    • while/for ϧʔϓ ېࢭ
    • null ېࢭ
    • Option.get ېࢭ
    • return ېࢭ
    • if ېࢭ (൒෼৑ஊ)
    ࣾ಺Ͱ͸పఈͯ͠·͢
    

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25. ຊ೔ͷScalaจ๏͓͠ͳ͕͖
    • ग़ྗ
    • ม਺
    • ؔ਺Ϧςϥϧ
    • ίϨΫγϣϯ
    • ύλʔϯϚον
    

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26. ඪ४ग़ྗ
    scala> println("Hello, Scala!")
    Hello, Scala!
    scala> print("Hello, Scala!”)
    Hello, Scala!
    

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27. ඪ४ग़ྗ
    scala> println("Hello, Scala!")
    Hello, Scala!
    scala> print("Hello, Scala!”)
    Hello, Scala!
    վߦ΋Ұॹʹग़ྗ͞ΕΔ
    

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28. ຊ೔ͷScalaจ๏͓͠ͳ͕͖
    • ग़ྗ
    • ม਺
    • ؔ਺Ϧςϥϧ
    • ίϨΫγϣϯ
    • ύλʔϯϚον
    

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29. ม਺એݴ
    • val
    • ࠶୅ೖෆՄೳʢImmutableʣ
    • var
    • ࠶୅ೖՄೳʢMutableʣ
    

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30. ม਺એݴ
    scala> val lang = "scala"
    lang: String = scala
    

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31. ม਺એݴ
    scala> val lang = "scala"
    lang: String = scala
    scala> lang = "java"
    :8: error: reassignment to val
    lang = "java"
    ^
    

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32. ม਺એݴ
    scala> val lang = "scala"
    lang: String = scala
    scala> lang = "java"
    :8: error: reassignment to val
    lang = "java"
    ^
    ࠶୅ೖෆՄ
    

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33. ม਺એݴ
    scala> val lang = "scala"
    lang: String = scala
    scala> lang = "java"
    :8: error: reassignment to val
    lang = "java"
    ^
    scala> var lang = "php"
    lang: String = php
    ࠶୅ೖෆՄ
    

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34. ม਺એݴ
    scala> val lang = "scala"
    lang: String = scala
    scala> lang = "java"
    :8: error: reassignment to val
    lang = "java"
    ^
    scala> var lang = "php"
    lang: String = php
    scala> lang = "ruby"
    lang: String = ruby
    ࠶୅ೖෆՄ
    

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35. ม਺એݴ
    scala> val lang = "scala"
    lang: String = scala
    scala> lang = "java"
    :8: error: reassignment to val
    lang = "java"
    ^
    scala> var lang = "php"
    lang: String = php
    scala> lang = "ruby"
    lang: String = ruby
    ࠶୅ೖෆՄ
    ࠶୅ೖՄ
    

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36. ܕͷ͋Δม਺એݴ
    • val ม਺໊: ܕ = ஋
    • ࠶୅ೖෆՄೳʢImmutableʣ
    • var ม਺໊: ܕ = ஋
    • ࠶୅ೖՄೳʢMutableʣ
    

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37. ܕͷ͋Δม਺એݴ
    scala> val num0: Int = 1
    num0: Int = 1
    

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38. ܕͷ͋Δม਺એݴ
    scala> val num0: Int = 1
    num0: Int = 1
    

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39. ܕͷ͋Δม਺એݴ
    scala> val num0: Int = 1
    num0: Int = 1
    scala> val num0: Int = "1"
    :7: error: type mismatch;
    found : String("1")
    required: Int
    val num0: Int = "1"
    ^
    

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40. ܕͷ͋Δม਺એݴ
    scala> val num0: Int = 1
    num0: Int = 1
    scala> val num0: Int = "1"
    :7: error: type mismatch;
    found : String("1")
    required: Int
    val num0: Int = "1"
    ^
    ܕ͕ҟͳΔ
    

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41. ܕͷ͋Δม਺એݴ
    scala> val num0: Int = 1
    num0: Int = 1
    scala> val num0: Int = "1"
    :7: error: type mismatch;
    found : String("1")
    required: Int
    val num0: Int = "1"
    ^
    scala> val num0: String = "1"
    num0: String = 1
    ܕ͕ҟͳΔ
    

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42. ຊ೔ͷScalaจ๏͓͠ͳ͕͖
    • ग़ྗ
    • ม਺
    • ؔ਺Ϧςϥϧ
    • ίϨΫγϣϯ
    • ύλʔϯϚον
    

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43. Ϧςϥϧͬͯͳʹʁ
    • ม਺
    • ม਺͸ϓϩάϥϜͷϩδοΫͷதʹ஋Λ௚઀ॻ
    ͔ͣʹҰ౓୅ೖͨ͠΋ͷΛ࢖͏͜ͱ
    • Ϧςϥϧ
    • ϓϩάϥϜͷதʹ਺ࣈ΍จࣈͳͲͷ஋Λ

    ௚઀ॻ͍ͨఆ਺ͷ͜ͱ
    

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44. Ϧςϥϧͬͯͳʹʁ
    • ม਺
    • ม਺͸ϓϩάϥϜͷϩδοΫͷதʹ஋Λ௚઀ॻ
    ͔ͣʹҰ౓୅ೖͨ͠΋ͷΛ࢖͏͜ͱ
    • Ϧςϥϧ
    • ϓϩάϥϜͷதʹ਺ࣈ΍จࣈͳͲͷ஋Λ

    ௚઀ॻ͍ͨఆ਺ͷ͜ͱ
    ରٛޠ
    

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45. Ϧςϥϧͬͯͳʹʁ
    scala> 12345
    res0: Int = 12345
    scala> "BizReach"
    res1: String = BizReach
    ੔਺Ϧςϥϧ
    จࣈྻϦςϥϧ
    

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46. ؔ਺Ϧςϥϧ
    • ؔ਺ΛҰ౓ม਺ʹ୅ೖͤͣʢ໊લΛ෇͚ͣʣ
    ʹϓϩάϥϜͷதʹ௚઀ॻ͘͜ͱ
    Y*OU
    Y
    

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47. ؔ਺Ϧςϥϧ
    • ؔ਺ΛҰ౓ม਺ʹ୅ೖͤͣʢ໊લΛ෇͚ͣʣ
    ʹϓϩάϥϜͷதʹ௚઀ॻ͘͜ͱ
    Y*OU
    Y
    ؔ਺ʹ౉͢஋
    

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48. ؔ਺Ϧςϥϧ
    • ؔ਺ΛҰ౓ม਺ʹ୅ೖͤͣʢ໊લΛ෇͚ͣʣ
    ʹϓϩάϥϜͷதʹ௚઀ॻ͘͜ͱ
    Y*OU
    Y
    ؔ਺ʹ౉͢஋
    ౉͢஋ͷܕ
    

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49. ؔ਺Ϧςϥϧ
    • ؔ਺ΛҰ౓ม਺ʹ୅ೖͤͣʢ໊લΛ෇͚ͣʣ
    ʹϓϩάϥϜͷதʹ௚઀ॻ͘͜ͱ
    Y*OU
    Y
    ؔ਺ʹ౉͢஋
    ౉͢஋ͷܕ
    

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50. ؔ਺Ϧςϥϧ
    • ؔ਺ΛҰ౓ม਺ʹ୅ೖͤͣʢ໊લΛ෇͚ͣʣ
    ʹϓϩάϥϜͷதʹ௚઀ॻ͘͜ͱ
    Y*OU
    Y
    ؔ਺ʹ౉͢஋
    ౉͢஋ͷܕ
    ؔ਺ͷॲཧͱ݁Ռ
    

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51. ؔ਺Ϧςϥϧ
    scala> val plus = (x:Int, y:Int) => x + y
    plus: (Int, Int) => Int =
    

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52. ؔ਺Ϧςϥϧ
    scala> val plus = (x:Int, y:Int) => x + y
    plus: (Int, Int) => Int =
    ؔ਺ϦςϥϧΛ
    

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53. ؔ਺Ϧςϥϧ
    scala> val plus = (x:Int, y:Int) => x + y
    plus: (Int, Int) => Int =
    ؔ਺ϦςϥϧΛ
    ม਺ʹ୅ೖ
    

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54. ؔ਺Ϧςϥϧ
    scala> val plus = (x:Int, y:Int) => x + y
    plus: (Int, Int) => Int =
    scala> val sum = (x: Int, y: Int) => {
    | println("x is " + x)
    | println("y is " + y)
    | x + y
    | }
    sum: (Int, Int) => Int =
    ؔ਺ϦςϥϧΛ
    ม਺ʹ୅ೖ
    

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55. ؔ਺Ϧςϥϧ
    scala> val plus = (x:Int, y:Int) => x + y
    plus: (Int, Int) => Int =
    scala> val sum = (x: Int, y: Int) => {
    | println("x is " + x)
    | println("y is " + y)
    | x + y
    | }
    sum: (Int, Int) => Int =
    ؔ਺ϦςϥϧΛ
    ม਺ʹ୅ೖ
    ෳ਺ߦͷ৔߹
    

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56. ؔ਺Ϧςϥϧ
    scala> val plus = (x:Int, y:Int) => x + y
    plus: (Int, Int) => Int =
    scala> val sum = (x: Int, y: Int) => {
    | println("x is " + x)
    | println("y is " + y)
    | x + y
    | }
    sum: (Int, Int) => Int =
    scala> sum(2, 3)
    x is 2
    y is 3
    res4: Int = 5
    ؔ਺ϦςϥϧΛ
    ม਺ʹ୅ೖ
    ෳ਺ߦͷ৔߹
    ࠷ޙͷߦ͕ධՁ͞ΕΔ
    

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57. defΩʔϫʔυΛ࢖ͬͨؔ਺ఆٛ
    object Untitled {
    def main(args:Array[String]) = {
    def plus(x: Int, y: Int):Int = {
    x + y
    }
    }
    }
    

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58. defΩʔϫʔυΛ࢖ͬͨؔ਺ఆٛ
    object Untitled {
    def main(args:Array[String]) = {
    def plus(x: Int, y: Int):Int = {
    x + y
    }
    }
    }
    ໭Γ஋ͷܕ
    

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59. ຊ೔ͷScalaจ๏͓͠ͳ͕͖
    • ग़ྗ
    • ม਺
    • ؔ਺Ϧςϥϧ
    • ίϨΫγϣϯ
    • ύλʔϯϚον
    

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60. ίϨΫγϣϯ
    • List
    • Range
    • Tuple
    

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61. ίϨΫγϣϯ
    • List
    • Range
    • Tuple
    ࠓ೔͸͜Ε͚ͩ
    

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62. List
    scala> List(0, 1, 2, 3)
    res0: List[Int] = List(0, 1, 2, 3)
    

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63. List
    scala> List(0, 1, 2, 3)
    res0: List[Int] = List(0, 1, 2, 3)
    جຊతͳListͷ࡞Γํ
    

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64. List
    scala> List(0, 1, 2, 3)
    res0: List[Int] = List(0, 1, 2, 3)
    scala> Nil
    res1: scala.collection.immutable.Nil.type = List()
    جຊతͳListͷ࡞Γํ
    

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65. List
    scala> List(0, 1, 2, 3)
    res0: List[Int] = List(0, 1, 2, 3)
    scala> Nil
    res1: scala.collection.immutable.Nil.type = List()
    جຊతͳListͷ࡞Γํ
    ۭͷϦετͷ࡞Γํ
    

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66. List
    scala> List(0, 1, 2, 3)
    res0: List[Int] = List(0, 1, 2, 3)
    scala> Nil
    res1: scala.collection.immutable.Nil.type = List()
    scala> val ls: List[Int] = List(1, 2, 3)
    ls: List[Int] = List(1, 2, 3)
    جຊతͳListͷ࡞Γํ
    ۭͷϦετͷ࡞Γํ
    

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67. List
    scala> List(0, 1, 2, 3)
    res0: List[Int] = List(0, 1, 2, 3)
    scala> Nil
    res1: scala.collection.immutable.Nil.type = List()
    scala> val ls: List[Int] = List(1, 2, 3)
    ls: List[Int] = List(1, 2, 3)
    جຊతͳListͷ࡞Γํ
    ۭͷϦετͷ࡞Γํ
    ܕΛએݴͯ͠ม਺ʹ୅ೖ
    

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68. List
    scala> List(0, 1, 2, 3)
    res0: List[Int] = List(0, 1, 2, 3)
    scala> Nil
    res1: scala.collection.immutable.Nil.type = List()
    scala> val ls: List[Int] = List(1, 2, 3)
    ls: List[Int] = List(1, 2, 3)
    scala> val ls0 = 0 :: ls
    ls0: List[Int] = List(0, 1, 2, 3)
    جຊతͳListͷ࡞Γํ
    ۭͷϦετͷ࡞Γํ
    ܕΛએݴͯ͠ม਺ʹ୅ೖ
    

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69. List
    scala> List(0, 1, 2, 3)
    res0: List[Int] = List(0, 1, 2, 3)
    scala> Nil
    res1: scala.collection.immutable.Nil.type = List()
    scala> val ls: List[Int] = List(1, 2, 3)
    ls: List[Int] = List(1, 2, 3)
    scala> val ls0 = 0 :: ls
    ls0: List[Int] = List(0, 1, 2, 3)
    جຊతͳListͷ࡞Γํ
    ۭͷϦετͷ࡞Γํ
    ܕΛએݴͯ͠ม਺ʹ୅ೖ
    Ϧετͷઌ಄ʹ௥Ճ͢Δ஋::ListͰ
    ৽͍͠ϦετΛͭ͘Γͬ·͢
    

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70. List
    scala> List(0, 1, 2, 3)
    res0: List[Int] = List(0, 1, 2, 3)
    scala> Nil
    res1: scala.collection.immutable.Nil.type = List()
    scala> val ls: List[Int] = List(1, 2, 3)
    ls: List[Int] = List(1, 2, 3)
    scala> val ls0 = 0 :: ls
    ls0: List[Int] = List(0, 1, 2, 3)
    scala> 0 :: 1 :: 2 :: 3 :: Nil
    res2: List[Int] = List(0, 1, 2, 3)
    جຊతͳListͷ࡞Γํ
    ۭͷϦετͷ࡞Γํ
    ܕΛએݴͯ͠ม਺ʹ୅ೖ
    Ϧετͷઌ಄ʹ௥Ճ͢Δ஋::ListͰ
    ৽͍͠ϦετΛͭ͘Γͬ·͢
    

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71. List
    scala> List(0, 1, 2, 3)
    res0: List[Int] = List(0, 1, 2, 3)
    scala> Nil
    res1: scala.collection.immutable.Nil.type = List()
    scala> val ls: List[Int] = List(1, 2, 3)
    ls: List[Int] = List(1, 2, 3)
    scala> val ls0 = 0 :: ls
    ls0: List[Int] = List(0, 1, 2, 3)
    scala> 0 :: 1 :: 2 :: 3 :: Nil
    res2: List[Int] = List(0, 1, 2, 3)
    جຊతͳListͷ࡞Γํ
    ۭͷϦετͷ࡞Γํ
    ܕΛએݴͯ͠ม਺ʹ୅ೖ
    Ϧετͷઌ಄ʹ௥Ճ͢Δ஋::ListͰ
    ৽͍͠ϦετΛͭ͘Γͬ·͢
    ۭͷϦετʹରͯ͠஋Λ௥Ճͨ͠Γ
    ෳ਺ͷ஋Λ::Ͱ௥Ճग़དྷ·͢
    

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72. Range
    scala> 1 to 10
    

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73. Range
    scala> 1 to 10
    res0: scala.collection.immutable.Range.Inclusive =
    Range(1, 2, 3, 4, 5, 6, 7, 8, 9, 10)
    1͔Β10·Ͱͷ੔਺ྻ
    

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74. Range
    scala> 1 to 10
    res0: scala.collection.immutable.Range.Inclusive =
    Range(1, 2, 3, 4, 5, 6, 7, 8, 9, 10)
    scala> 1 until 10
    res1: scala.collection.immutable.Range =
    Range(1, 2, 3, 4, 5, 6, 7, 8, 9)
    1͔Β10·Ͱͷ੔਺ྻ
    

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75. Range
    scala> 1 to 10
    res0: scala.collection.immutable.Range.Inclusive =
    Range(1, 2, 3, 4, 5, 6, 7, 8, 9, 10)
    scala> 1 until 10
    res1: scala.collection.immutable.Range =
    Range(1, 2, 3, 4, 5, 6, 7, 8, 9)
    1͔Β10·Ͱͷ੔਺ྻ
    1͔Β10ະຬͷ੔਺ྻ
    

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76. Range
    scala> 1 to 10
    res0: scala.collection.immutable.Range.Inclusive =
    Range(1, 2, 3, 4, 5, 6, 7, 8, 9, 10)
    scala> 1 until 10
    res1: scala.collection.immutable.Range =
    Range(1, 2, 3, 4, 5, 6, 7, 8, 9)
    scala> 1 to 10 by 2
    res2: scala.collection.immutable.Range =
    Range(1, 3, 5, 7, 9)
    1͔Β10·Ͱͷ੔਺ྻ
    1͔Β10ະຬͷ੔਺ྻ
    

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77. Range
    scala> 1 to 10
    res0: scala.collection.immutable.Range.Inclusive =
    Range(1, 2, 3, 4, 5, 6, 7, 8, 9, 10)
    scala> 1 until 10
    res1: scala.collection.immutable.Range =
    Range(1, 2, 3, 4, 5, 6, 7, 8, 9)
    scala> 1 to 10 by 2
    res2: scala.collection.immutable.Range =
    Range(1, 3, 5, 7, 9)
    1͔Β10·Ͱͷ੔਺ྻ
    1͔Β10ະຬͷ੔਺ྻ
    1͔Β10·Ͱެࠩ2ͷ౳ࠩ਺ྻ
    

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78. Tuple
    scala> ("JAVA", "Eclipse")
    res0: (String, String) = (JAVA,Eclipse)
    scala> ("Scala", "IntelliJ")
    res1: (String, String) = (Scala,IntelliJ)
    

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79. Tuple
    scala> ("JAVA", "Eclipse")
    res0: (String, String) = (JAVA,Eclipse)
    scala> ("Scala", "IntelliJ")
    res1: (String, String) = (Scala,IntelliJ)
    ஋ͷηοτͰ͢
    

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80. Tuple
    scala> ("JAVA", "Eclipse")
    res0: (String, String) = (JAVA,Eclipse)
    scala> ("Scala", "IntelliJ")
    res1: (String, String) = (Scala,IntelliJ)
    scala> ("Apple", "Orange", "Banana")
    res2: (String, String, String) = (Apple,Orange,Banana)
    ஋ͷηοτͰ͢
    ෳ਺ͷ஋Λ·ͱΊΔ
    

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81. Tuple
    scala> ("JAVA", "Eclipse")
    res0: (String, String) = (JAVA,Eclipse)
    scala> ("Scala", "IntelliJ")
    res1: (String, String) = (Scala,IntelliJ)
    scala> ("Apple", "Orange", "Banana")
    res2: (String, String, String) = (Apple,Orange,Banana)
    scala> List(("Apple", "Orange"), ("Strawberry", “Cherry"))
    res3: List[(String, String)] = List((Apple,Orange),
    (Strawberry,Cherry))
    ஋ͷηοτͰ͢
    ෳ਺ͷ஋Λ·ͱΊΔ
    λϓϧͷϦετΛ࡞Δ
    

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82. Tuple
    scala> ("JAVA", "Eclipse")
    res0: (String, String) = (JAVA,Eclipse)
    scala> ("Scala", "IntelliJ")
    res1: (String, String) = (Scala,IntelliJ)
    scala> ("Apple", "Orange", "Banana")
    res2: (String, String, String) = (Apple,Orange,Banana)
    scala> List(("Apple", "Orange"), ("Strawberry", “Cherry"))
    res3: List[(String, String)] = List((Apple,Orange),
    (Strawberry,Cherry))
    ஋ͷηοτͰ͢
    ෳ਺ͷ஋Λ·ͱΊΔ
    λϓϧͷϦετΛ࡞Δ
    ܕ͸͜ͷΑ͏ʹͳΓ·͢
    

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83. ຊ೔ͷScalaจ๏͓͠ͳ͕͖
    • ग़ྗ
    • ม਺
    • ؔ਺Ϧςϥϧ
    • ίϨΫγϣϯ
    • ύλʔϯϚον
    

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84. ύλʔϯϚον
    object Untitled {
    def main(args:Array[String]) = {
    val lang = "Scala"
    lang match {
    case "Java" => println("Eclipse")
    case "Scala" => println("IntelliJ")
    case "PHP" | "Ruby"=> println("CodeRunner")
    case _ => println("Vim")
    }
    }
    }
    

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85. ύλʔϯϚον
    object Untitled {
    def main(args:Array[String]) = {
    val lang = "Scala"
    lang match {
    case "Java" => println("Eclipse")
    case "Scala" => println("IntelliJ")
    case "PHP" | "Ruby"=> println("CodeRunner")
    case _ => println("Vim")
    }
    }
    }
    “IntelliJ”͕ग़ྗ͞ΕΔ
    

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86. ύλʔϯϚον
    object Untitled {
    def main(args:Array[String]) = {
    val lang:String = "Scala"
    val ide:String = lang match {
    case "Java" => "Eclipse"
    case "Scala" => "IntelliJ"
    case "PHP" | "Ruby"=> "CodeRunner"
    case _ => "Vim"
    }
    println("Use "+ ide +".")
    }
    }
    

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87. ύλʔϯϚον
    object Untitled {
    def main(args:Array[String]) = {
    val lang:String = "Scala"
    val ide:String = lang match {
    case "Java" => "Eclipse"
    case "Scala" => "IntelliJ"
    case "PHP" | "Ruby"=> "CodeRunner"
    case _ => "Vim"
    }
    println("Use "+ ide +".")
    }
    }
    ஋Λฦ͢͜ͱ΋Ͱ͖·͢
    

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88. ύλʔϯϚον
    object Untitled {
    def main(args:Array[String]) = {
    val lang:String = "Scala"
    val ide:String = lang match {
    case "Java" => "Eclipse"
    case "Scala" => "IntelliJ"
    case "PHP" | "Ruby"=> "CodeRunner"
    case _ => "Vim"
    }
    println("Use "+ ide +".")
    }
    }
    ஋Λฦ͢͜ͱ΋Ͱ͖·͢
    “Use IntelliJ.”͕ग़ྗ͞ΕΔ
    

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89. Functional Programming?
    

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90. ࣸ૾ͷΠϝʔδ
    • ͋Δू߹ͷཁૉͦΕͧΕʹ
    

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91. ࣸ૾ͷΠϝʔδ
    • ͋Δू߹ͷཁૉͦΕͧΕʹ
    • ԿΒ͔ͷޮՌΛద༻͢Δ͜ͱͰ
    

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92. ࣸ૾ͷΠϝʔδ
    • ͋Δू߹ͷཁૉͦΕͧΕʹ
    • ԿΒ͔ͷޮՌΛద༻͢Δ͜ͱͰ
    • ৽͍͠ू߹Λͭ͘Δ
    

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93. ࣸ૾ͷΠϝʔδ
    x1
    x2
    x3
    

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94. ࣸ૾ͷΠϝʔδ
    x1
    x2
    x3
    function
    

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95. ࣸ૾ͷΠϝʔδ
    x1
    x2
    x3
    y1
    function
    

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96. ࣸ૾ͷΠϝʔδ
    x1
    x2
    x3
    y1
    function
    function
    

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97. ࣸ૾ͷΠϝʔδ
    x1
    x2
    x3
    y1
    y2
    y3
    function
    function
    

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98. ͨͱ͑͹SNSͰ
    ڞ௨ͷ༑ਓΛݟ͚ͭΔͱ͖
    

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99. ڞ௨ͷ༑ਓΛݟ͚ͭΔ
    ࣗ෼ͷ༑ਓ ༑ਓͷ༑ਓ
    

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100. ڞ௨ͷ༑ਓΛݟ͚ͭΔ
     ࣗ෼ͷ༑ਓ ༑ਓͷ༑ਓ
     

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101. ڞ௨ͷ༑ਓΛݟ͚ͭΔ
     ࣗ෼ͷ༑ਓ ༑ਓͷ༑ਓ
     

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102. A͘Μͱͷ
     ڞ௨ͷ༑ਓΛݟ͚ͭΔ
     ͢΂ͯͷ
     Ϣʔβʔ
     

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103. A͘Μͱͷ
     ڞ௨ͷ༑ਓΛݟ͚ͭΔ
     friends(me)
     ͢΂ͯͷ
     Ϣʔβʔ
     

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104. A͘Μͱͷ
     ڞ௨ͷ༑ਓΛݟ͚ͭΔ
     friends(me)
     ͢΂ͯͷ
     Ϣʔβʔ
     ࢲͷ༑ਓ
     

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105. A͘Μͱͷ
     ڞ௨ͷ༑ਓΛݟ͚ͭΔ
     friends(me)
     ͢΂ͯͷ
     Ϣʔβʔ
     friends(A)
     ࢲͷ༑ਓ
     

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106. A͘Μͱͷ
     ڞ௨ͷ༑ਓΛݟ͚ͭΔ
     friends(me)
     ͢΂ͯͷ
     Ϣʔβʔ
     friends(A)
     ࢲͷ༑ਓ
     

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107. A͘Μͱͷ
     ڞ௨ͷ༑ਓΛݟ͚ͭΔ
     friends(me)
     ͢΂ͯͷ
     Ϣʔβʔ
     friends(A)
     ࢲͷ༑ਓ
     ڞ௨
     ͷ༑ਓ
     

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108. ؔ਺ܕϓϩάϥϛϯά
     • એݴܕϓϩάϥϛϯά
     • ؔ਺͸ୈҰڃΦϒδΣΫτ
     • λʢϥϜμʣ
     • ࢀরಁաੑ
     • ෭࡞༻ͷͳ͍ؔ਺ɺࣜ
     • ஗ԆධՁ
     • Ϟφυ
     

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109. ͜ΕΒͷཧ࿦ΛॳΊͯฉ͍ͯ
     ཧղͰ͖·͔͢ʁ
     

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110. ղͤ͵
     ϞφυͬͯͳΜͩΑ(ʋ´ω`)
     

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111. ؔ਺ܕΛΠϝʔδ͢ΔͨΊʹ͸
     • ߴߍͰͳΒͬͨू߹Λࢥ͍ग़͠·͠ΐ͏
     

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112. Collection API
     

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113. Collectionʢࣸ૾ʣΛૢ࡞͢Δ
     4ͭͷϝιου
     • foreach
     • reduce
     • filter
     • map
     

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114. Collectionʢࣸ૾ʣΛૢ࡞͢Δ
     4ͭͷϝιου
     • foreach
     • reduce
     • filter
     • map
     

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115. foreach
     scala> val langs = List("Java", "Scala", "PHP")
     langs: List[String] = List(Java, Scala, PHP)
     

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116. foreach
     scala> val langs = List("Java", "Scala", "PHP")
     langs: List[String] = List(Java, Scala, PHP)
     ListΛͭ͘Γ·͢
     

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117. foreach
     scala> val langs = List("Java", "Scala", "PHP")
     langs: List[String] = List(Java, Scala, PHP)
     scala> langs.foreach ( )
     ListΛͭ͘Γ·͢
     

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118. foreach
     scala> val langs = List("Java", "Scala", "PHP")
     langs: List[String] = List(Java, Scala, PHP)
     scala> langs.foreach ( x => println(x) )
     ListΛͭ͘Γ·͢
     

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119. foreach
     scala> val langs = List("Java", "Scala", "PHP")
     langs: List[String] = List(Java, Scala, PHP)
     scala> langs.foreach ( x => println(x) )
     ListΛͭ͘Γ·͢
     ؔ਺ϦςϥϧΛ౉͠·͢
     

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120. foreach
     scala> val langs = List("Java", "Scala", "PHP")
     langs: List[String] = List(Java, Scala, PHP)
     scala> langs.foreach ( x => println(x) )
     Java
     Scala
     PHP
     ListΛͭ͘Γ·͢
     ؔ਺ϦςϥϧΛ౉͠·͢
     Listͷઌ಄͔ΒॱʹɺҾ਺ʹड͚औͬͨؔ਺Λద༻͠·͢
     

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121. Collectionʢࣸ૾ʣΛૢ࡞͢Δ
     4ͭͷϝιου
     • foreach
     • reduce
     • filter
     • map
     

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122. reduce
     scala> val range = List(1, 2, 3, 4, 5, 6, 7, 8, 9, 10)
     

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123. reduce
     scala> val range = List(1, 2, 3, 4, 5, 6, 7, 8, 9, 10)
     range: List[Int] = List(1, 2, 3, 4, 5, 6, 7, 8, 9, 10)
     1͔Β10·ͰͷListΛͭ͘Δ
     

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124. reduce
     scala> val range = List(1, 2, 3, 4, 5, 6, 7, 8, 9, 10)
     range: List[Int] = List(1, 2, 3, 4, 5, 6, 7, 8, 9, 10)
     scala> range.reduce( )
     1͔Β10·ͰͷListΛͭ͘Δ
     

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125. reduce
     scala> val range = List(1, 2, 3, 4, 5, 6, 7, 8, 9, 10)
     range: List[Int] = List(1, 2, 3, 4, 5, 6, 7, 8, 9, 10)
     scala> range.reduce( )
     1͔Β10·ͰͷListΛͭ͘Δ
     

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126. reduce
     scala> val range = List(1, 2, 3, 4, 5, 6, 7, 8, 9, 10)
     range: List[Int] = List(1, 2, 3, 4, 5, 6, 7, 8, 9, 10)
     scala> range.reduce( (x0, x1) => x0 + x1 )
     res1: Int = 55
     1͔Β10·ͰͷListΛͭ͘Δ
     

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127. reduce
     scala> val range = List(1, 2, 3, 4, 5, 6, 7, 8, 9, 10)
     range: List[Int] = List(1, 2, 3, 4, 5, 6, 7, 8, 9, 10)
     scala> range.reduce( (x0, x1) => x0 + x1 )
     res1: Int = 55
     1͔Β10·ͰͷListΛͭ͘Δ
     Ҿ਺Λ2ͭऔΔؔ਺ϦςϥϧΛ౉͢
     

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128. reduce
     scala> val range = List(1, 2, 3, 4, 5, 6, 7, 8, 9, 10)
     range: List[Int] = List(1, 2, 3, 4, 5, 6, 7, 8, 9, 10)
     scala> range.reduce( (x0, x1) => x0 + x1 )
     res1: Int = 55
     1͔Β10·ͰͷListΛͭ͘Δ
     Ҿ਺Λ2ͭऔΔؔ਺ϦςϥϧΛ౉͢
     

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129. reduce
     scala> val range = List(1, 2, 3, 4, 5, 6, 7, 8, 9, 10)
     range: List[Int] = List(1, 2, 3, 4, 5, 6, 7, 8, 9, 10)
     scala> range.reduce( (x0, x1) => x0 + x1 )
     res1: Int = 55
     1͔Β10·ͰͷListΛͭ͘Δ
     Ҿ਺Λ2ͭऔΔؔ਺ϦςϥϧΛ౉͢
     

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130. reduce
     scala> val range = List(1, 2, 3, 4, 5, 6, 7, 8, 9, 10)
     range: List[Int] = List(1, 2, 3, 4, 5, 6, 7, 8, 9, 10)
     scala> range.reduce( (x0, x1) => x0 + x1 )
     res1: Int = 55
     1͔Β10·ͰͷListΛͭ͘Δ
     Ҿ਺Λ2ͭऔΔؔ਺ϦςϥϧΛ౉͢
     

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131. reduce
     scala> val range = List(1, 2, 3, 4, 5, 6, 7, 8, 9, 10)
     range: List[Int] = List(1, 2, 3, 4, 5, 6, 7, 8, 9, 10)
     scala> range.reduce( (x0, x1) => x0 + x1 )
     res1: Int = 55
     1͔Β10·ͰͷListΛͭ͘Δ
     Ҿ਺Λ2ͭऔΔؔ਺ϦςϥϧΛ౉͢
     ઌ಄͔Βॱʹɺܭࢉ݁Ռͱ࣍ͷ஋Λ
     ౉͞Εͨؔ਺Ϧςϥϧʹద༻ͨ݁͠ՌΛฦ͢
     

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132. Collectionʢࣸ૾ʣΛૢ࡞͢Δ
     4ͭͷϝιου
     • foreach
     • reduce
     • filter
     • map
     

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133. filter
     scala> val range = List(1, 2, 3, 4, 5, 6, 7, 8, 9, 10)
     range: List[Int] = List(1, 2, 3, 4, 5, 6, 7, 8, 9, 10)
     

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134. filter
     scala> val range = List(1, 2, 3, 4, 5, 6, 7, 8, 9, 10)
     range: List[Int] = List(1, 2, 3, 4, 5, 6, 7, 8, 9, 10)
     scala> val odd = range.filter( )
     

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135. filter
     scala> val range = List(1, 2, 3, 4, 5, 6, 7, 8, 9, 10)
     range: List[Int] = List(1, 2, 3, 4, 5, 6, 7, 8, 9, 10)
     scala> val odd = range.filter( x => x % 2 == 1 )
     BooleanΛฦؔ͢਺ϦςϥϧΛ౉͢
     

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136. filter
     scala> val range = List(1, 2, 3, 4, 5, 6, 7, 8, 9, 10)
     range: List[Int] = List(1, 2, 3, 4, 5, 6, 7, 8, 9, 10)
     scala> val odd = range.filter( x => x % 2 == 1 )
     scala> val odd = range.filter( x => x % 2 == 1 )
     odd: List[Int] = List(1, 3, 5, 7, 9)
     BooleanΛฦؔ͢਺ϦςϥϧΛ౉͢
     ح਺ͷίϨΫγϣϯ͕࡞ΒΕͨ
     

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137. Collectionʢࣸ૾ʣΛૢ࡞͢Δ
     4ͭͷϝιου
     • foreach
     • reduce
     • filter
     • map
     

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138. map
     scala> val range = List(1, 2, 3, 4, 5, 6, 7, 8, 9, 10)
     range: List[Int] = List(1, 2, 3, 4, 5, 6, 7, 8, 9, 10)
     

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139. map
     scala> val range = List(1, 2, 3, 4, 5, 6, 7, 8, 9, 10)
     range: List[Int] = List(1, 2, 3, 4, 5, 6, 7, 8, 9, 10)
     scala> val twoTimes = range.map( )
     

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140. map
     scala> val range = List(1, 2, 3, 4, 5, 6, 7, 8, 9, 10)
     range: List[Int] = List(1, 2, 3, 4, 5, 6, 7, 8, 9, 10)
     scala> val twoTimes = range.map( x => x * 2 )
     

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141. map
     scala> val range = List(1, 2, 3, 4, 5, 6, 7, 8, 9, 10)
     range: List[Int] = List(1, 2, 3, 4, 5, 6, 7, 8, 9, 10)
     scala> val twoTimes = range.map( x => x * 2 )
     ஋Λड͚औΓɺ৽͍͠஋Λฦؔ͢਺ϦςϥϧΛ౉͢
     

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142. map
     scala> val range = List(1, 2, 3, 4, 5, 6, 7, 8, 9, 10)
     range: List[Int] = List(1, 2, 3, 4, 5, 6, 7, 8, 9, 10)
     scala> val twoTimes = range.map( x => x * 2 )
     twoTimes: List[Int] =
     List(2, 4, 6, 8, 10, 12, 14, 16, 18, 20)
     ஋Λड͚औΓɺ৽͍͠஋Λฦؔ͢਺ϦςϥϧΛ౉͢
     ΋ͱͷίϨΫγϣϯͷ஋ΛͦΕͧΕ2ഒͨ͠ίϨΫγϣϯ͕ͭ͘ΒΕͨ
     

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143. Practice!
     

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144. ࿅श໰୊
     • 1͔Β100·Ͱͷ੔਺Λग़ྗ͢Δ
     • 1͔Β100·Ͱͷ੔਺Λͨ͠߹ΘͤΔ
     • 1͔Β100·Ͱͷۮ਺Λͨ͠߹ΘͤΔ
     • 1͔Β100·Ͱͷ੔਺ͰFizzBuzz
     

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145. ࿅श໰୊
     • 1͔Β100·Ͱͷ੔਺Λग़ྗ͢Δ
     • 1͔Β100·Ͱͷ੔਺Λͨ͠߹ΘͤΔ
     • 1͔Β100·Ͱͷۮ਺Λͨ͠߹ΘͤΔ
     • 1͔Β100·Ͱͷ੔਺ͰFizzBuzz
     

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146. CollectionΛૢ࡞͢Δ
     4ͭͷϝιου
     • foreach
     • reduce, fold
     • filter
     • map
     

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147. 1͔Β100·Ͱͷ੔਺Λग़ྗ
     • ·ͣ͸͓޷͖ͳݴޠͰॻ͍ͯΈ͍ͯͩ͘͞
     

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148. 1͔Β100·Ͱͷ੔਺Λग़ྗ
     # PHP
     for ($i = 1; $i <= 100; $i++) {
     print $i . "\n";
     }
     ?>
     

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149. 1͔Β100·Ͱͷ੔਺Λग़ྗ
     # Scala
     object Print {
     def main(args: Array[String]) {
     (1 to 100).foreach(println)
     }
     }
     

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150. 1͔Β100·Ͱͷ੔਺Λग़ྗ
     # Scala
     object Print {
     def main(args: Array[String]) {
     (1 to 100).foreach(println)
     }
     }
     x => println(x) ͷΑ͏ʹؔ਺͕
     ஋ΛऔΔ͜ͱ͕໌Β͔ͳͱ͖͸লུՄ
     

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151. ࿅श໰୊
     • 1͔Β100·Ͱͷ੔਺Λग़ྗ͢Δ
     • 1͔Β100·Ͱͷ੔਺Λͨ͠߹ΘͤΔ
     • 1͔Β100·Ͱͷۮ਺Λͨ͠߹ΘͤΔ
     • 1͔Β100·Ͱͷ੔਺ͰFizzBuzz
     

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152. CollectionΛૢ࡞͢Δ
     4ͭͷϝιου
     • foreach
     • reduce
     • filter
     • map
     

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153. 1͔Β100ͷ੔਺Λͨ͠߹ΘͤΔ
     # PHP
     for($i = 1, $sum = 0; $i <= 100; $i++) {
     $sum += $i;
     }
     echo($sum);
     ?>
     

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154. 1͔Β100ͷ੔਺Λͨ͠߹ΘͤΔ
     # Sclala
     object Sum {
     def main(args: Array[String]) {
     val sum =
     (1 to 100).reduce((x0, x1) => x0 + x1)
     println(sum)
     }
     }
     

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155. 1͔Β100ͷ੔਺Λͨ͠߹ΘͤΔ
     # Sclala
     object Sum {
     def main(args: Array[String]) {
     val sum =
     (1 to 100).reduce((x0, x1) => x0 + x1)
     println(sum)
     }
     }
     RangeΛ͔ͬ͜ͰғΜͰ࢖͑·͢
     

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156. 1͔Β100ͷ੔਺Λͨ͠߹ΘͤΔ
     # Sclala
     object Sum {
     def main(args: Array[String]) {
     val sum = (x0: Int, x1: Int) => x0 + x1
     val result = (1 to 100).reduce(sum)
     println(result)
     }
     }
     

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157. 1͔Β100ͷ੔਺Λͨ͠߹ΘͤΔ
     # Sclala
     object Sum {
     def main(args: Array[String]) {
     val sum = (x0: Int, x1: Int) => x0 + x1
     val result = (1 to 100).reduce(sum)
     println(result)
     }
     }
     ؔ਺Λม਺ʹ୅ೖͯ͠ɺ
     ͜ΕΛ౉͢͜ͱ΋ग़དྷ·͢
     

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158. ࿅श໰୊
     • 1͔Β100·Ͱͷ੔਺Λग़ྗ͢Δ
     • 1͔Β100·Ͱͷ੔਺Λͨ͠߹ΘͤΔ
     • 1͔Β100·Ͱͷۮ਺Λͨ͠߹ΘͤΔ
     • 1͔Β100·Ͱͷ੔਺ͰFizzBuzz
     

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159. CollectionΛૢ࡞͢Δ
     4ͭͷϝιου
     • foreach
     • reduce
     • filter
     • map
     

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160. 1͔Β100·Ͱͷۮ਺Λͨ͠߹ΘͤΔ
     # PHP
     for ($i = 2, $sum = 0; $i <= 100; $i += 2) {
     $sum += $i;
     }
     print($sum);
     ?>
     

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161. 1͔Β100·Ͱͷۮ਺Λͨ͠߹ΘͤΔ
     # Scala
     object SumEven {
     def main(args: Array[String]) {
     val sum = (x0: Int, x1: Int) => x0 + x1
     val isEven = (x: Int) => x % 2 == 0
     // (1 to 100).filter(x => x % 2 == 0).reduce(_ + _)
     val result = (1 to 100).filter(isEven).reduce(sum)
     println(result)
     }
     }
     ίϨΫγϣϯϝιουΛνΣʔϯ͢Δ͜ͱ΋Ͱ͖·͢
     

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162. 1͔Β100·Ͱͷۮ਺Λͨ͠߹ΘͤΔ
     # Scala
     object SumEven {
     def main(args: Array[String]) {
     val result = (2 to 100 by 2).sum
     println(result)
     }
     }
     

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163. 1͔Β100·Ͱͷۮ਺Λͨ͠߹ΘͤΔ
     # Scala
     object SumEven {
     def main(args: Array[String]) {
     val result = (2 to 100 by 2).sum
     println(result)
     }
     }
     ίϨΫγϣϯʹ͸σϑΥϧτͰ
     ଟ͘ͷϝιου͕༻ҙ͞Ε͍ͯ·͢
     

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164. ࿅श໰୊
     • 1͔Β100·Ͱͷ੔਺Λग़ྗ͢Δ
     • 1͔Β100·Ͱͷ੔਺Λͨ͠߹ΘͤΔ
     • 1͔Β100·Ͱͷۮ਺Λͨ͠߹ΘͤΔ
     • 1͔Β100·Ͱͷ੔਺ͰFizzBuzz
     

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165. FizzBuzzͷϧʔϧ
     • 1͔Β100·Ͱͷ੔਺Λग़ྗ͢Δ
     • ͨͩ͠3ͷഒ਺ͷͱ͖͸Fizz
     • 5ͷഒ਺ͷͱ͖͸Buzz
     • 3ͱ5ͷഒ਺ͷͱ͖͸FizzBuzz
     • ਺ࣈΛจࣈྻʹஔ͖͔͑ͯग़ྗ͢Δ
     

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166. FizzBuzzͷΠϝʔδ
     • 1, 2, Fizz, 4, Buzz, Fizz, 7, 8, Fizz, Buzz,

     11, Fizz, 13, 14, FizzBuzz, …
     

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167. 1͔Β100·Ͱͷ੔਺ͰFizzBuzz
     # PHP
     for ($i = 0; $i < 100; $i ++) {
     if (($i % 3) === 0 && ($i % 5) === 0) {
     print("FizzBuzz".",");
     }
     else if($i % 3 === 0) {
     print("Fizz".",");
     }
     else if ($i % 5 === 0) {
     print("Buzz".",");
     }
     else {
     print($i.",");
     }
     }
     ?>
     

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168. 1͔Β100·Ͱͷ੔਺ͰFizzBuzz
     # Scala
     object FizzBuzz {
     def main(args:Array[String]) = {
     val fizzBuzz = (x: Int) => ( x%3, x%5 ) match {
     case (0, 0) => "FizzBuzz"
     case (0, _) => "Fizz"
     case (_, 0) => "Buzz"
     case _ => x.toString
     }
     val result = (1 to 100).map(fizzBuzz).mkString(",")
     println(result)
     }
     }
     

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169. 1͔Β100·Ͱͷ੔਺ͰFizzBuzz
     # Scala
     object FizzBuzz {
     def main(args:Array[String]) = {
     val fizzBuzz = (x: Int) => ( x%3, x%5 ) match {
     case (0, 0) => "FizzBuzz"
     case (0, _) => "Fizz"
     case (_, 0) => "Buzz"
     case _ => x.toString
     }
     val result = (1 to 100).map(fizzBuzz).mkString(",")
     println(result)
     }
     }
     xΛ3Ͱׂͬͨ͋·Γͱɺ
     5Ͱׂͬͨ͋·ΓͷTuple
     

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170. 1͔Β100·Ͱͷ੔਺ͰFizzBuzz
     # Scala
     object FizzBuzz {
     def main(args:Array[String]) = {
     val fizzBuzz = (x: Int) => ( x%3, x%5 ) match {
     case (0, 0) => "FizzBuzz"
     case (0, _) => "Fizz"
     case (_, 0) => "Buzz"
     case _ => x.toString
     }
     val result = (1 to 100).map(fizzBuzz).mkString(",")
     println(result)
     }
     }
     xΛ3Ͱׂͬͨ͋·Γͱɺ
     5Ͱׂͬͨ͋·ΓͷTuple
     Tupleͷ஋ͰύλʔϯϚον
     ͢Δ͜ͱ΋Ͱ͖Δ
     

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171. 1͔Β100·Ͱͷ੔਺ͰFizzBuzz
     # Scala
     object FizzBuzz {
     def main(args:Array[String]) = {
     val fizzBuzz = (x: Int) => ( x%3, x%5 ) match {
     case (0, 0) => "FizzBuzz"
     case (0, _) => "Fizz"
     case (_, 0) => "Buzz"
     case _ => x.toString
     }
     val result = (1 to 100).map(fizzBuzz).mkString(",")
     println(result)
     }
     }
     fizzBuzzม਺ʹ౉͞Ε͍ͯΔ
     ͷ͸ؔ਺Ϧςϥϧ
     

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172. Recursive
     

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173. ࠶ؼͷ͸ͳ͠
     • ͨͱ͑͹ɺ͋Δؔ਺͕ͦͷهड़ͷͳ͔Ͱ

     ࣗ෼ࣗ৴Λؔ਺ͱͯ͠ݺͼग़͢͜ͱɻ

     

     def recursive = {

     …

     recursive(xx)

     }
     

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174. ຤ඌ࠶ؼ
     • ؔ਺ͷఆٛͰɺ࠶ؼΛ༻͍Δͱ͖͸ɺ

     ࣗ෼ࣗ਎ͷݺͼग़͠͸ɺ

     ؔ਺ఆٛͷͷ࠷ޙʹ͢Δɻ
     • ຤ඌ࠶ؼҎ֎ͷ࠶ؼͰ͸ɺ

     ࠶ؼݺͼग़͠ͷͨͼʹελοΫΛͭ͘ΔͨΊ

     ΦʔόʔϑϩʔΛى͜͢ةݥ͕͋Γ·͢ɻ
     

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175. ֊৐ܭࢉͷྫ
     • ࣗવ਺ n ͷ֊৐ެࣜ

     n! = n * (n - 1) * … * 1
     • ͜ΕΛܭࢉ͢Δؔ਺Λఆٛ͢Δ

     ʢ 0! = 1 ʣ
     

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176. ֊৐ܭࢉͷྫ
     object Untitled {
     def main(args:Array[String]) = {
     def factorial(n:Int):Int =
     if (n < 1) 1 else (n * factorial(n - 1))
     println(factorial(1)) // 1
     println(factorial(2)) // 2
     println(factorial(3)) // 6
     println(factorial(4)) // 24
     }
     }
     

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177. ֊৐ܭࢉͷྫ
     object Untitled {
     def main(args:Array[String]) = {
     def factorial(n:Int):Int =
     if (n < 1) 1 else (n * factorial(n - 1))
     println(factorial(1)) // 1
     println(factorial(2)) // 2
     println(factorial(3)) // 6
     println(factorial(4)) // 24
     }
     }
     ຤ඌ࠶ؼ͡Όͳ͍
     

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178. ֊৐ܭࢉʢ຤ඌ࠶ؼʣ
     object Untitled {
     def main(args:Array[String]) = {
     def factorial(n:Int, acc:Int = 1):Int =
     if (n < 1) acc else (factorial(n - 1, n * acc))
     println(factorial(1)) // 1
     println(factorial(2)) // 2
     println(factorial(3)) // 6
     println(factorial(4)) // 24
     }
     }
     

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179. ֊৐ܭࢉʢ຤ඌ࠶ؼʣ
     object Untitled {
     def main(args:Array[String]) = {
     def factorial(n:Int, acc:Int = 1):Int =
     if (n < 1) acc else (factorial(n - 1, n * acc))
     println(factorial(1)) // 1
     println(factorial(2)) // 2
     println(factorial(3)) // 6
     println(factorial(4)) // 24
     }
     }
     ΞΩϡϜϨʔλͷಋೖ
     

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180. ֊৐ܭࢉʢ຤ඌ࠶ؼʣ
     object Untitled {
     def main(args:Array[String]) = {
     def factorial(n:Int, acc:Int = 1):Int =
     if (n < 1) acc else (factorial(n - 1, n * acc))
     println(factorial(1)) // 1
     println(factorial(2)) // 2
     println(factorial(3)) // 6
     println(factorial(4)) // 24
     }
     }
     ΞΩϡϜϨʔλͷಋೖ
     ͜ΕͰ຤ඌ࠶ؼʹͳͬͨ
     

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181. Practice!
     

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182. ϑΟϘφον਺
     • n ൪໨ͷϑΟϘφον਺ΛF_nͰද͢ͱ
     • F_0 = 0
     • F_1 = 1
     • F_n+2 = F_n + F_n+1 (n >= 0)
     

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183. ϑΟϘφον਺ྻͷΠϝʔδ
     • 0, 1, 1, 2, 3, 5, 8, 13, 21, 34, 55, 89, 144, 233,
     377, 610, 987, 1597, 2584, 4181, 6765,
     10946, …
     

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184. ϑΟϘφον਺ͷ໰୊
     • ϑΟϘφον਺ͷ n ൪໨ͷ஋Λ

     ٻΊΔؔ਺Λͭ͘Δ

     

     fib(0) = 0

     fib(1) = 1

     fib(2) = 1

     fib(3) = 2
     

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185. ϑΟϘφον਺ͷྫ
     object Fibonacci {
     def main(args:Array[String]) = {
     def fib(n: Int): Int = if(n < 1) 0 else n match {
     case 1 => 1
     case 2 => 1
     case x => fib(x-1) + fib(x-2)
     }
     val fibString = (1 to 10).map(fib).mkString(", ")
     println(fibString)
     // 1, 1, 2, 3, 5, 8, 13, 21, 34, 55
     }
     }
     ຤ඌ࠶ؼ͡Όͳ͍
     

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186. ϑΟϘφον਺ʢ຤ඌ࠶ؼʣ
     object Fibonacci {
     def main(args:Array[String]) = {
     def fibList(lim: Int): List[Int] = {
     def fib0(lim: Int, fls: List[Int]): List[Int] = {
     if (lim < 1) fls else {
     fls match {
     case Nil => fib0(lim-1, 1 :: Nil)
     case x0 :: Nil => fib0(lim-1, 1 :: fls)
     case x1 :: x0 :: ls => fib0(lim-1, (x0 + x1) :: x1 :: x0 :: ls)
     }
     }
     }
     fib0(lim, Nil).reverse
     }
     def fib(n: Int): Int = fibList(n).last
     }
     }
     fibListͷ಺෦ʹؔ਺Λ࡞Δ
     fib0ͷͳ͔Ͱ͸ٯॱͰListΛ͍ͭͬͯ͘ΔͨΊɺ࠷ޙʹ໭͢
     

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187. ϑΟϘφον਺ྻʢ lazy val ʣ
     val fibList = (lim: Int) => {
     lazy val fib0:(Int, List[Int]) => List[Int] = (lim:Int, fls:List[Int]) =>
     {
     if (lim < 1) fls else {
     fls match {
     case Nil => fib0(lim-1, 1 :: Nil)
     case x0 :: Nil => fib0(lim-1, 1 :: fls)
     case x1 :: x0 :: ls => fib0(lim-1, (x0 + x1) :: x1 :: x0 :: ls)
     }
     }
     }
     fib0(lim, Nil).reverse
     }
     val fib = (n: Int) => fibList(n).last
     .lastOption.getOrElse(0)
     

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188. ͓͠·͍
     

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