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͡Ίͯͷؔܕ
ϓϩάϥϛϯάڭࣨ
Hands-on Functional Programming in Scala
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ຊ͢͜ͱ
• ײ֮తʹཧղ͢Δؔܕϓϩάϥϛϯά
• ίϨΫγϣϯͷ͜ͱ
• ύλʔϯϚονͷ͜ͱ
• ࠶ؼͷ͜ͱ
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ຊ͞ͳ͍͜ͱ
• Scalaͷ࣮༻తͳจ๏
• Ϋϩʔδϟ
• ෦ద༻
• ΧϦʔԽ
• ϞφυͳͲ
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ScalaΛಈ͔͢·Ͱ
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Mac OSΛ͓͍ͷํ
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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Mac OSΛ͓͍ͷํ
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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WindowsΛ͓͍ͷํ
• JDKΠϯετʔϧʢJava SEʣ
http://www.oracle.com/technetwork/jp/java/javase/downloads/index.html
• ScalaΠϯετʔϧ
http://www.scala-lang.org/download/
• ڥมΛઃఆ
ίϯτϩʔϧύωϧʼγεςϜʼγεςϜͷৄࡉઃఆ
Ϣʔβʔఆٛڥมʹ৽نՃʢ໊લPATHʹઃఆʣ
JDKΛΠϯετʔϧͨ͠ϑΥϧμԼbin·Ͱͷύε;ʢʀͰ۠Δʣ
ScalaΛΠϯετʔϧͨ͠ϑΥϧμԼͷbin·Ͱͷύε
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ڥߏங͕໘͍͘͞ํ
• ΦϯϥΠϯͷScala࣮ߦڥ͕͋Γ·͢
• tutorialspoint.com
• paiza.io
• codebunk.com
• scastie.org
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ศརͳπʔϧ
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“Hello Scala!”
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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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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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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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IDE
object Main {
def main(args: Array[String]) {
println("Hello, Scala!")
}
}
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IDE
object Main {
def main(args: Array[String]) {
println("Hello, Scala!")
}
}
͓·͡ͳ͍
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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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15ͰֶͿ Scala
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ຊͷScalaจ๏͓͠ͳ͕͖
• ग़ྗ
• ม
• ؔϦςϥϧ
• ίϨΫγϣϯ
• ύλʔϯϚον
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ຊͷScalaจ๏͓͠ͳ͕͖
• ग़ྗ
• ม
• ؔϦςϥϧ
• ίϨΫγϣϯ
• ύλʔϯϚον
ࠓ͜Ε͚ͩ
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Scalaͷ͍͍ͱ͜Ζ
• ܕਪ (Type Inference)
• ϓϨʔεϗϧμʔ
• ҥߏจ (Syntactic sugar)
• ڧྗͳύλʔϯϚον
• ҉ͷܕม (Implicit Conversions)
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ScalaٯҾ͖Ϩγϐ
ఴथʗౡຊଟՄࢠ ஶ
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ScalaٯҾ͖Ϩγϐ
ఴथʗౡຊଟՄࢠ ஶ
ৄͪ͘͜͠Β
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Scala ΫϨυ
• var ېࢭ
• mutable ېࢭ
• while/for ϧʔϓ ېࢭ
• null ېࢭ
• Option.get ېࢭ
• return ېࢭ
• if ېࢭ (ஊ)
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Scala ΫϨυ
• var ېࢭ
• mutable ېࢭ
• while/for ϧʔϓ ېࢭ
• null ېࢭ
• Option.get ېࢭ
• return ېࢭ
• if ېࢭ (ஊ)
ࣾͰపఈͯ͠·͢
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ຊͷScalaจ๏͓͠ͳ͕͖
• ग़ྗ
• ม
• ؔϦςϥϧ
• ίϨΫγϣϯ
• ύλʔϯϚον
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ඪ४ग़ྗ
scala> println("Hello, Scala!")
Hello, Scala!
scala> print("Hello, Scala!”)
Hello, Scala!
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ඪ४ग़ྗ
scala> println("Hello, Scala!")
Hello, Scala!
scala> print("Hello, Scala!”)
Hello, Scala!
վߦҰॹʹग़ྗ͞ΕΔ
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ຊͷScalaจ๏͓͠ͳ͕͖
• ग़ྗ
• ม
• ؔϦςϥϧ
• ίϨΫγϣϯ
• ύλʔϯϚον
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มએݴ
• val
• ࠶ೖෆՄೳʢImmutableʣ
• var
• ࠶ೖՄೳʢMutableʣ
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มએݴ
scala> val lang = "scala"
lang: String = scala
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มએݴ
scala> val lang = "scala"
lang: String = scala
scala> lang = "java"
:8: error: reassignment to val
lang = "java"
^
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มએݴ
scala> val lang = "scala"
lang: String = scala
scala> lang = "java"
:8: error: reassignment to val
lang = "java"
^
࠶ೖෆՄ
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มએݴ
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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มએݴ
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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มએݴ
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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ܕͷ͋Δมએݴ
• val ม໊: ܕ =
• ࠶ೖෆՄೳʢImmutableʣ
• var ม໊: ܕ =
• ࠶ೖՄೳʢMutableʣ
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ܕͷ͋Δมએݴ
scala> val num0: Int = 1
num0: Int = 1
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ܕͷ͋Δมએݴ
scala> val num0: Int = 1
num0: Int = 1
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ܕͷ͋Δมએݴ
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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ܕͷ͋Δมએݴ
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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ܕͷ͋Δมએݴ
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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ຊͷScalaจ๏͓͠ͳ͕͖
• ग़ྗ
• ม
• ؔϦςϥϧ
• ίϨΫγϣϯ
• ύλʔϯϚον
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Ϧςϥϧͬͯͳʹʁ
• ม
• มϓϩάϥϜͷϩδοΫͷதʹΛॻ
͔ͣʹҰೖͨ͠ͷΛ͏͜ͱ
• Ϧςϥϧ
• ϓϩάϥϜͷதʹࣈจࣈͳͲͷΛ
ॻ͍ͨఆͷ͜ͱ
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Ϧςϥϧͬͯͳʹʁ
• ม
• มϓϩάϥϜͷϩδοΫͷதʹΛॻ
͔ͣʹҰೖͨ͠ͷΛ͏͜ͱ
• Ϧςϥϧ
• ϓϩάϥϜͷதʹࣈจࣈͳͲͷΛ
ॻ͍ͨఆͷ͜ͱ
ରٛޠ
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Ϧςϥϧͬͯͳʹʁ
scala> 12345
res0: Int = 12345
scala> "BizReach"
res1: String = BizReach
Ϧςϥϧ
จࣈྻϦςϥϧ
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ؔϦςϥϧ
• ؔΛҰมʹೖͤͣʢ໊લΛ͚ͣʣ
ʹϓϩάϥϜͷதʹॻ͘͜ͱ
Y*OU
Y
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ؔϦςϥϧ
• ؔΛҰมʹೖͤͣʢ໊લΛ͚ͣʣ
ʹϓϩάϥϜͷதʹॻ͘͜ͱ
Y*OU
Y
ؔʹ͢
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ؔϦςϥϧ
• ؔΛҰมʹೖͤͣʢ໊લΛ͚ͣʣ
ʹϓϩάϥϜͷதʹॻ͘͜ͱ
Y*OU
Y
ؔʹ͢
͢ͷܕ
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ؔϦςϥϧ
• ؔΛҰมʹೖͤͣʢ໊લΛ͚ͣʣ
ʹϓϩάϥϜͷதʹॻ͘͜ͱ
Y*OU
Y
ؔʹ͢
͢ͷܕ
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ؔϦςϥϧ
• ؔΛҰมʹೖͤͣʢ໊લΛ͚ͣʣ
ʹϓϩάϥϜͷதʹॻ͘͜ͱ
Y*OU
Y
ؔʹ͢
͢ͷܕ
ؔͷॲཧͱ݁Ռ
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ؔϦςϥϧ
scala> val plus = (x:Int, y:Int) => x + y
plus: (Int, Int) => Int =
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ؔϦςϥϧ
scala> val plus = (x:Int, y:Int) => x + y
plus: (Int, Int) => Int =
ؔϦςϥϧΛ
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ؔϦςϥϧ
scala> val plus = (x:Int, y:Int) => x + y
plus: (Int, Int) => Int =
ؔϦςϥϧΛ
มʹೖ
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ؔ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
มʹೖ
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ؔ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
มʹೖ
ෳߦͷ߹
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ؔ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
มʹೖ
ෳߦͷ߹
࠷ޙͷߦ͕ධՁ͞ΕΔ
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defΩʔϫʔυΛͬͨؔఆٛ
object Untitled {
def main(args:Array[String]) = {
def plus(x: Int, y: Int):Int = {
x + y
}
}
}
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defΩʔϫʔυΛͬͨؔఆٛ
object Untitled {
def main(args:Array[String]) = {
def plus(x: Int, y: Int):Int = {
x + y
}
}
}
Γͷܕ
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ຊͷScalaจ๏͓͠ͳ͕͖
• ग़ྗ
• ม
• ؔϦςϥϧ
• ίϨΫγϣϯ
• ύλʔϯϚον
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ίϨΫγϣϯ
• List
• Range
• Tuple
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ίϨΫγϣϯ
• List
• Range
• Tuple
ࠓ͜Ε͚ͩ
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List
scala> List(0, 1, 2, 3)
res0: List[Int] = List(0, 1, 2, 3)
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List
scala> List(0, 1, 2, 3)
res0: List[Int] = List(0, 1, 2, 3)
جຊతͳListͷ࡞Γํ
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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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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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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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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
ܕΛએݴͯ͠มʹೖ
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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
ܕΛએݴͯ͠มʹೖ
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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
ܕΛએݴͯ͠มʹೖ
Ϧετͷઌ಄ʹՃ͢Δ::ListͰ
৽͍͠ϦετΛͭ͘Γͬ·͢
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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
ܕΛએݴͯ͠มʹೖ
Ϧετͷઌ಄ʹՃ͢Δ::ListͰ
৽͍͠ϦετΛͭ͘Γͬ·͢
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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
ܕΛએݴͯ͠มʹೖ
Ϧετͷઌ಄ʹՃ͢Δ::ListͰ
৽͍͠ϦετΛͭ͘Γͬ·͢
ۭͷϦετʹରͯ͠ΛՃͨ͠Γ
ෳͷΛ::ͰՃग़དྷ·͢
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Range
scala> 1 to 10
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Range
scala> 1 to 10
res0: scala.collection.immutable.Range.Inclusive =
Range(1, 2, 3, 4, 5, 6, 7, 8, 9, 10)
1͔Β10·Ͱͷྻ
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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·Ͱͷྻ
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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·Ͱͷྻ
1͔Β10ະຬͷྻ
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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·Ͱͷྻ
1͔Β10ະຬͷྻ
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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·Ͱͷྻ
1͔Β10ະຬͷྻ
1͔Β10·Ͱެࠩ2ͷࠩྻ
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Tuple
scala> ("JAVA", "Eclipse")
res0: (String, String) = (JAVA,Eclipse)
scala> ("Scala", "IntelliJ")
res1: (String, String) = (Scala,IntelliJ)
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Tuple
scala> ("JAVA", "Eclipse")
res0: (String, String) = (JAVA,Eclipse)
scala> ("Scala", "IntelliJ")
res1: (String, String) = (Scala,IntelliJ)
ͷηοτͰ͢
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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
ෳͷΛ·ͱΊΔ
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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
ෳͷΛ·ͱΊΔ
λϓϧͷϦετΛ࡞Δ
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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
ෳͷΛ·ͱΊΔ
λϓϧͷϦετΛ࡞Δ
ܕ͜ͷΑ͏ʹͳΓ·͢
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ຊͷScalaจ๏͓͠ͳ͕͖
• ग़ྗ
• ม
• ؔϦςϥϧ
• ίϨΫγϣϯ
• ύλʔϯϚον
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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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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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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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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 +".")
}
}
Λฦ͢͜ͱͰ͖·͢
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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 +".")
}
}
Λฦ͢͜ͱͰ͖·͢
“Use IntelliJ.”͕ग़ྗ͞ΕΔ
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Functional Programming?
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ࣸ૾ͷΠϝʔδ
• ͋Δू߹ͷཁૉͦΕͧΕʹ
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ࣸ૾ͷΠϝʔδ
• ͋Δू߹ͷཁૉͦΕͧΕʹ
• ԿΒ͔ͷޮՌΛద༻͢Δ͜ͱͰ
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ࣸ૾ͷΠϝʔδ
• ͋Δू߹ͷཁૉͦΕͧΕʹ
• ԿΒ͔ͷޮՌΛద༻͢Δ͜ͱͰ
• ৽͍͠ू߹Λͭ͘Δ
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ࣸ૾ͷΠϝʔδ
x1
x2
x3
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ࣸ૾ͷΠϝʔδ
x1
x2
x3
function
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ࣸ૾ͷΠϝʔδ
x1
x2
x3
y1
function
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ࣸ૾ͷΠϝʔδ
x1
x2
x3
y1
function
function
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ࣸ૾ͷΠϝʔδ
x1
x2
x3
y1
y2
y3
function
function
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ͨͱ͑SNSͰ
ڞ௨ͷ༑ਓΛݟ͚ͭΔͱ͖
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ڞ௨ͷ༑ਓΛݟ͚ͭΔ
ࣗͷ༑ਓ ༑ਓͷ༑ਓ
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ڞ௨ͷ༑ਓΛݟ͚ͭΔ
ࣗͷ༑ਓ ༑ਓͷ༑ਓ
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ڞ௨ͷ༑ਓΛݟ͚ͭΔ
ࣗͷ༑ਓ ༑ਓͷ༑ਓ
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A͘Μͱͷ
ڞ௨ͷ༑ਓΛݟ͚ͭΔ
ͯ͢ͷ
Ϣʔβʔ
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A͘Μͱͷ
ڞ௨ͷ༑ਓΛݟ͚ͭΔ
friends(me)
ͯ͢ͷ
Ϣʔβʔ
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A͘Μͱͷ
ڞ௨ͷ༑ਓΛݟ͚ͭΔ
friends(me)
ͯ͢ͷ
Ϣʔβʔ
ࢲͷ༑ਓ
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A͘Μͱͷ
ڞ௨ͷ༑ਓΛݟ͚ͭΔ
friends(me)
ͯ͢ͷ
Ϣʔβʔ
friends(A)
ࢲͷ༑ਓ
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A͘Μͱͷ
ڞ௨ͷ༑ਓΛݟ͚ͭΔ
friends(me)
ͯ͢ͷ
Ϣʔβʔ
friends(A)
ࢲͷ༑ਓ
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A͘Μͱͷ
ڞ௨ͷ༑ਓΛݟ͚ͭΔ
friends(me)
ͯ͢ͷ
Ϣʔβʔ
friends(A)
ࢲͷ༑ਓ
ڞ௨
ͷ༑ਓ
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ؔܕϓϩάϥϛϯά
• એݴܕϓϩάϥϛϯά
• ؔୈҰڃΦϒδΣΫτ
• λʢϥϜμʣ
• ࢀরಁաੑ
• ෭࡞༻ͷͳ͍ؔɺࣜ
• ԆධՁ
• Ϟφυ
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͜ΕΒͷཧΛॳΊͯฉ͍ͯ
ཧղͰ͖·͔͢ʁ
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ղͤ͵
ϞφυͬͯͳΜͩΑ(ʋ´ω`)
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ؔܕΛΠϝʔδ͢ΔͨΊʹ
• ߴߍͰͳΒͬͨू߹Λࢥ͍ग़͠·͠ΐ͏
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Collection API
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Collectionʢࣸ૾ʣΛૢ࡞͢Δ
4ͭͷϝιου
• foreach
• reduce
• filter
• map
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Collectionʢࣸ૾ʣΛૢ࡞͢Δ
4ͭͷϝιου
• foreach
• reduce
• filter
• map
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foreach
scala> val langs = List("Java", "Scala", "PHP")
langs: List[String] = List(Java, Scala, PHP)
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foreach
scala> val langs = List("Java", "Scala", "PHP")
langs: List[String] = List(Java, Scala, PHP)
ListΛͭ͘Γ·͢
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foreach
scala> val langs = List("Java", "Scala", "PHP")
langs: List[String] = List(Java, Scala, PHP)
scala> langs.foreach ( )
ListΛͭ͘Γ·͢
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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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foreach
scala> val langs = List("Java", "Scala", "PHP")
langs: List[String] = List(Java, Scala, PHP)
scala> langs.foreach ( x => println(x) )
ListΛͭ͘Γ·͢
ؔϦςϥϧΛ͠·͢
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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·͢
ؔϦςϥϧΛ͠·͢
Listͷઌ಄͔ΒॱʹɺҾʹड͚औͬͨؔΛద༻͠·͢
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Collectionʢࣸ૾ʣΛૢ࡞͢Δ
4ͭͷϝιου
• foreach
• reduce
• filter
• map
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reduce
scala> val range = List(1, 2, 3, 4, 5, 6, 7, 8, 9, 10)
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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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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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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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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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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
ҾΛ2ͭऔΔؔϦςϥϧΛ͢
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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
ҾΛ2ͭऔΔؔϦςϥϧΛ͢
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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
ҾΛ2ͭऔΔؔϦςϥϧΛ͢
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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
ҾΛ2ͭऔΔؔϦςϥϧΛ͢
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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
ҾΛ2ͭऔΔؔϦςϥϧΛ͢
ઌ಄͔Βॱʹɺܭࢉ݁Ռͱ࣍ͷΛ
͞ΕͨؔϦςϥϧʹద༻ͨ݁͠ՌΛฦ͢
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Collectionʢࣸ૾ʣΛૢ࡞͢Δ
4ͭͷϝιου
• foreach
• reduce
• filter
• map
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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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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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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 )
BooleanΛฦؔ͢ϦςϥϧΛ͢
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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)
BooleanΛฦؔ͢ϦςϥϧΛ͢
حͷίϨΫγϣϯ͕࡞ΒΕͨ
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Collectionʢࣸ૾ʣΛૢ࡞͢Δ
4ͭͷϝιου
• foreach
• reduce
• filter
• map
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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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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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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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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৽͍͠Λฦؔ͢ϦςϥϧΛ͢
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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৽͍͠Λฦؔ͢ϦςϥϧΛ͢
ͱͷίϨΫγϣϯͷΛͦΕͧΕ2ഒͨ͠ίϨΫγϣϯ͕ͭ͘ΒΕͨ
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Practice!
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࿅श
• 1͔Β100·ͰͷΛग़ྗ͢Δ
• 1͔Β100·ͰͷΛͨ͠߹ΘͤΔ
• 1͔Β100·ͰͷۮΛͨ͠߹ΘͤΔ
• 1͔Β100·ͰͷͰFizzBuzz
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࿅श
• 1͔Β100·ͰͷΛग़ྗ͢Δ
• 1͔Β100·ͰͷΛͨ͠߹ΘͤΔ
• 1͔Β100·ͰͷۮΛͨ͠߹ΘͤΔ
• 1͔Β100·ͰͷͰFizzBuzz
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CollectionΛૢ࡞͢Δ
4ͭͷϝιου
• foreach
• reduce, fold
• filter
• map
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1͔Β100·ͰͷΛग़ྗ
• ·͓͖ͣͳݴޠͰॻ͍ͯΈ͍ͯͩ͘͞
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1͔Β100·ͰͷΛग़ྗ
# PHP
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1͔Β100·ͰͷΛग़ྗ
# Scala
object Print {
def main(args: Array[String]) {
(1 to 100).foreach(println)
}
}
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1͔Β100·ͰͷΛग़ྗ
# Scala
object Print {
def main(args: Array[String]) {
(1 to 100).foreach(println)
}
}
x => println(x) ͷΑ͏ʹ͕ؔ
ΛऔΔ͜ͱ͕໌Β͔ͳͱ͖লུՄ
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࿅श
• 1͔Β100·ͰͷΛग़ྗ͢Δ
• 1͔Β100·ͰͷΛͨ͠߹ΘͤΔ
• 1͔Β100·ͰͷۮΛͨ͠߹ΘͤΔ
• 1͔Β100·ͰͷͰFizzBuzz
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CollectionΛૢ࡞͢Δ
4ͭͷϝιου
• foreach
• reduce
• filter
• map
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1͔Β100ͷΛͨ͠߹ΘͤΔ
# PHP
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1͔Β100ͷΛͨ͠߹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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1͔Β100ͷΛͨ͠߹ΘͤΔ
# Sclala
object Sum {
def main(args: Array[String]) {
val sum =
(1 to 100).reduce((x0, x1) => x0 + x1)
println(sum)
}
}
RangeΛ͔ͬ͜ͰғΜͰ͑·͢
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1͔Β100ͷΛͨ͠߹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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1͔Β100ͷΛͨ͠߹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)
}
}
ؔΛมʹೖͯ͠ɺ
͜ΕΛ͢͜ͱग़དྷ·͢
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࿅श
• 1͔Β100·ͰͷΛग़ྗ͢Δ
• 1͔Β100·ͰͷΛͨ͠߹ΘͤΔ
• 1͔Β100·ͰͷۮΛͨ͠߹ΘͤΔ
• 1͔Β100·ͰͷͰFizzBuzz
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CollectionΛૢ࡞͢Δ
4ͭͷϝιου
• foreach
• reduce
• filter
• map
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1͔Β100·ͰͷۮΛͨ͠߹ΘͤΔ
# PHP
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1͔Β100·ͰͷۮΛͨ͠߹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)
}
}
ίϨΫγϣϯϝιουΛνΣʔϯ͢Δ͜ͱͰ͖·͢
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1͔Β100·ͰͷۮΛͨ͠߹ΘͤΔ
# Scala
object SumEven {
def main(args: Array[String]) {
val result = (2 to 100 by 2).sum
println(result)
}
}
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1͔Β100·ͰͷۮΛͨ͠߹ΘͤΔ
# Scala
object SumEven {
def main(args: Array[String]) {
val result = (2 to 100 by 2).sum
println(result)
}
}
ίϨΫγϣϯʹσϑΥϧτͰ
ଟ͘ͷϝιου͕༻ҙ͞Ε͍ͯ·͢
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࿅श
• 1͔Β100·ͰͷΛग़ྗ͢Δ
• 1͔Β100·ͰͷΛͨ͠߹ΘͤΔ
• 1͔Β100·ͰͷۮΛͨ͠߹ΘͤΔ
• 1͔Β100·ͰͷͰFizzBuzz
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FizzBuzzͷϧʔϧ
• 1͔Β100·ͰͷΛग़ྗ͢Δ
• ͨͩ͠3ͷഒͷͱ͖Fizz
• 5ͷഒͷͱ͖Buzz
• 3ͱ5ͷഒͷͱ͖FizzBuzz
• ࣈΛจࣈྻʹஔ͖͔͑ͯग़ྗ͢Δ
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FizzBuzzͷΠϝʔδ
• 1, 2, Fizz, 4, Buzz, Fizz, 7, 8, Fizz, Buzz,
11, Fizz, 13, 14, FizzBuzz, …
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1͔Β100·ͰͷͰFizzBuzz
# PHP
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1͔Β100·ͰͷͰFizzBuzz
# 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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1͔Β100·ͰͷͰFizzBuzz
# 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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1͔Β100·ͰͷͰFizzBuzz
# 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
TupleͷͰύλʔϯϚον
͢Δ͜ͱͰ͖Δ
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1͔Β100·ͰͷͰFizzBuzz
# 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)
}
}
fizzBuzzมʹ͞Ε͍ͯΔ
ͷؔϦςϥϧ
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Recursive
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࠶ؼͷͳ͠
• ͨͱ͑ɺ͋Δ͕ؔͦͷهड़ͷͳ͔Ͱ
ࣗࣗ৴Λؔͱͯ͠ݺͼग़͢͜ͱɻ
def recursive = {
…
recursive(xx)
}
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ඌ࠶ؼ
• ؔͷఆٛͰɺ࠶ؼΛ༻͍Δͱ͖ɺ
ࣗࣗͷݺͼग़͠ɺ
ؔఆٛͷͷ࠷ޙʹ͢Δɻ
• ඌ࠶ؼҎ֎ͷ࠶ؼͰɺ
࠶ؼݺͼग़͠ͷͨͼʹελοΫΛͭ͘ΔͨΊ
ΦʔόʔϑϩʔΛى͜͢ةݥ͕͋Γ·͢ɻ
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֊ܭࢉͷྫ
• ࣗવ n ͷ֊ެࣜ
n! = n * (n - 1) * … * 1
• ͜ΕΛܭࢉ͢ΔؔΛఆٛ͢Δ
ʢ 0! = 1 ʣ
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֊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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֊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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֊ܭࢉʢඌ࠶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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֊ܭࢉʢඌ࠶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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֊ܭࢉʢඌ࠶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
͜ΕͰඌ࠶ؼʹͳͬͨ
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Practice!
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ϑΟϘφον
• n ൪ͷϑΟϘφονΛF_nͰද͢ͱ
• F_0 = 0
• F_1 = 1
• F_n+2 = F_n + F_n+1 (n >= 0)
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ϑΟϘφονྻͷΠϝʔδ
• 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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ϑΟϘφονͷ
• ϑΟϘφονͷ n ൪ͷΛ
ٻΊΔؔΛͭ͘Δ
fib(0) = 0
fib(1) = 1
fib(2) = 1
fib(3) = 2
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ϑΟϘφονͷྫ
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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ϑΟϘφονʢඌ࠶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
}
}
fibListͷ෦ʹؔΛ࡞Δ
fib0ͷͳ͔ͰٯॱͰListΛ͍ͭͬͯ͘ΔͨΊɺ࠷ޙʹ͢
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ϑΟϘφονྻʢ 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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͓͠·͍