KotlinプログラマのためのScala入門（１）〜基本編〜 ref: http://qiita.com/kmizu/items/9d16360c4d383f3fa2aa

file0.txt

val i = 1
println(i) // 1
i = i + 1 // コンパイルエラー
var j = 1
println(j) // 1
j = j + 1 // OK
println(j) // 2

file1.scala

val i = 1
println(i) // 1
i = i + 1 // コンパイルエラー
var j = 1
println(j) // 1
j = j + 1 // OK
println(j) // 2

file10.scala

sealed abstract class ParseResult[+T]
case class ParseSuccess[+T](value: T, next: String) extends ParseResult[T]
case class ParseFailure(message: String) extends ParseResult[Nothing]
val result: ParseResult[String] = ...
result match { // 通常、case classの中身をパターンマッチであらかじめ分解する
  case ParseSuccess(v, n) =>
  case ParseFailure(m) =>
}

file11.txt

sealed class ParseResult<out T> {
    data class ParseSuccess<out T>(val value: T, val next: String): ParseResult<T>()
    data class ParseFailure(val message: String): ParseResult<Nothing>()
}
val result: ParseResult<String> = ...
when(result) {
  is ParseResult.ParseSuccess -> // result: ParseSuccess
  is ParseResult.ParseFailure -> // result: ParseFailure
}

file12.txt

interface Foo {
  fun foo() {
    println("Foo")
  }
}

file13.scala

trait Foo {
  def foo(): Unit = {
    println("Foo")
  }
}

file14.txt

val s: String? = null
val s: String = "FOO"

file15.scala

val s: Option[String] = None
val s: String = "FOO"

file16.txt

val v = Integer.parseInt("100")

file17.scala

val v = Integer.parseInt("100")

file18.txt

val proc: () -> Int = { 1 }

file19.scala

val proc: () => Int = {() => 1}

file2.txt

val iLtj = if(i < j) "i < j" else "i >= j" // String
val x: Any = "FOO"
if(x is String) {
  // x はこの中ではString型
}

file20.txt

val power: (Int) -> Int = { it * it }

file21.scala

val power: Int => Int = {(it) => it * it}

file22.txt

class MyException(override val message: String): Exception(message)
throw MyException("Hoge")

file23.scala

class MyException(val message: String) extends Exception(message)
throw new MyException("Hoge")

file24.txt

fun foo(): Nothing = TODO()

file25.scala

def foo() = ???

file26.txt

val list = listOf(1, 2, 3)
list.filter{ it > 2 } // [3]

file27.scala

val list = List(1, 2, 3)
list.filter{it => it > 2} // List(3)

file3.scala

val iLtj = if(i < j) "i < j" else "i >= j" // String
val x: Any = "FOO"
x match {
  case x:String => // Scalaだと型に対するパターンマッチを使う
}

file4.txt

when(v) {
  0 -> ...
  1 -> ...
}

file5.scala

v match {
  case 0 => ...
  case 1 => ...
}

file6.txt

class Person(val name: String, val age: Int)

file7.scala

class Person(val name: String, val age: Int)

file8.txt

data class Person(val name: String, val age: Int)

file9.scala

case class Person(name: String, age: Int)