初心者向けScalaプロジェクト作成を行うハンズオン資料です. サンプルプログラムは (https://github.com/amaya382/scala-hands-on) を参照してください. (@Scala関西Summit 2017)

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scala
sbt about
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sbt new scala/hello-world.g8
cd sbt-example sbt
sbt run
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run
console
println("Hello")
Main.main(null)
:paste
:quit
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10. sbt-example/
├ build.sbt
├ project/
│ ├ build.properties
│ └ plugins.sbt
├ src/
│ ├ main/
│ │ └ scala/
│ │ └ Main.scala
│ └ test/
│ └ scala/
│ └ MainSpec.scala
└ target/
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12.
reload
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libraryDependencies ++= Seq(
"org.scala-sbt" %% "io" % "1.0.0",
"org.json4s" %% "json4s-jackson" % "3.5.2",
"org.scalatest" %% "scalatest" % "3.0.1" % Test)
reload
console
import sbt.io.IO
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def fizzBuzz(n: Int): Unit = ???
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object Main
extends App { ??? }
object Main {
def main(…): Unit =
{ ??? }
}

16. def fizzBuzz(n: Int): Unit =
for {i <- 1 to n} {
i match {
case x if x % 15 == 0 => println("FizzBuzz")
case x if x % 3 == 0 => println("Fizz")
case x if x % 5 == 0 => println("Buzz")
case x => println(x)
}
}
fizzBuzz(15)
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val pw = new
java.io.PrintWriter("sample.json")
pw.print(scala.io.Source.fromURL("h
ttps://goo.gl/KbGKi7").mkString)
pw.flush(); pw.close()

18.
def readFile(fileName: String)
: String = ???
import sbt.io.IO
IO.read
java.io.File
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19. import sbt.io.IO
import java.io.File
def readFile(fileName: String): String =
IO.read(new File(fileName))
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def parseIntArrayJSON(jsonString: String)
: List[Int] = ???
import org.json4s._
import org.json4s.jackson.JsonMethods
JsonMethods.parse
toInt
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21. import org.json4s._
import org.json4s.jackson.JsonMethods._
def parseIntArrayJSON(jsonString: String)
: List[Int] = {
val json = parse(jsonString)
for {
JArray(array) <- json
JInt(x) <- array
} yield x.toInt
}
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22.
def toFizzBuzz(ints: List[Int])
: List[String] = ???
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23. def toFizzBuzz(ints: List[Int])
: List[String] =
for {i <- ints}
yield i match {
case x if x % 15 == 0 => "FizzBuzz"
case x if x % 3 == 0 => "Fizz"
case x if x % 5 == 0 => "Buzz"
case x => x.toString
}
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24. def toFizzBuzz(ints: List[Int])
: List[String] =
ints.map(i =>
i match {
case x if x % 15 == 0 => "FizzBuzz"
case x if x % 3 == 0 => "Fizz"
case x if x % 5 == 0 => "Buzz"
case x => x.toString
})
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25. def toFizzBuzz(ints: List[Int])
: List[String] =
ints.map(i =>
i match {
case x if x % 15 == 0 => "FizzBuzz"
case x if x % 3 == 0 => "Fizz"
case x if x % 5 == 0 => "Buzz"
case x => x.toString
})
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26. def toFizzBuzz(ints: Seq[Int]): Seq[String] =
ints.map {
case x if x % 15 == 0 => "FizzBuzz"
case x if x % 3 == 0 => "Fizz"
case x if x % 5 == 0 => "Buzz"
case x => x.toString
}
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def toJSONFormat(list: List[String])
: String = ???
import org.json4s.JsonDSL._
render/compact
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28. import org.json4s.JsonDSL._
import org.json4s.jackson.JsonMethods._
def toJSONFormat(list: List[String]): String =
compact(render(list))
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def writeFile(fileName: String,
contents: String): Unit = ???
import sbt.io.IO
IO.write
java.io.File
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30. import sbt.io.IO
def writeFile(fileName: String,
contents: String): Unit =
IO.write(new File(fileName), contents)
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import org.scalatest._
class MainSpec extends FlatSpec { ... }
"foo" should "bar" in { ??? }
assert
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32. class MainSpec extends FlatSpec {!
"FizzBuzzed sample.json" should!
"have the same elements as answer.json" in {!
val sampleString = IO.read(new File("sample.json"))!
val sampleJSON = JsonMethods.parse(sampleString)!
val sample = for {!
JArray(arr) <- sampleJSON!
JInt(x) <- arr!
} yield x.toInt!
val fizzBuzzedSample = Main.toFizzBuzz(sample)!
val answerString = IO.read(new File("answer.json"))!
val answerJSON = JsonMethods.parse(answerString)!
val answer = for {!
JArray(arr) <- answerJSON!
JString(x) <- arr!
} yield x!
assert(!
fizzBuzzedSample.sameElements(answer))!
}!
}
import java.io.File!
import org.json4s._!
import org.json4s.jackson.JsonMethods!
import org.scalatest._!
import sbt.io.IO!
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addSbtPlugin("org.xerial.sbt" % "sbt-pack" % "0.9.0")
sbt pack
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