seratch/doc.md

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    Scala Introduction for Java developers

ScalaMatsuri 2017

prerequisites

JDK 8+ (if you'd like to use the latest Scala)
brew install sbt to install the global sbt launcher script

scala lang version
You can switch the version when starting the JVM.

2.11.x on Java 7
2.11.x on Java 8
2.12.x on Java 8

Scala lang binary version
Binary compatibilities are not kept between the bin versions.

2.9.0
2.9.1
2.9.2
2.10.x
2.11.x
2.12.x
2.13.x

Getting started

on the REPL: sbt console
Setup Atom + ENSIME (in Japanese): https://gist.github.com/seratch/cc472f64f72ba725360ee6517008e23c
IntelliJ IDEA (preparing sbt project and load it)

IntelliJ Setup Demo


# brew install sbt
mkdir -p hello-scala/project
cd hello-scala
echo 'sbt.version=0.13.13' > project/build.properties
echo 'scalaVersion := "2.12.1"' > build.sbt
sbt

Hello World
on the REPL
sbt console
# println("Hello World")

IntelliJ IDEA


Run
Debug

object Example extends App {
  println("Hello World!")
}

diff java scala

package, package object, import renamed package/class/trait
Immutable Collection, Option
class, trait, object
companion object for static things
test (ScalaTest, specs2)

Test Demo

http://www.scalatest.org/

echo 'libraryDependencies += "org.scalatest" %% "scalatest" % "3.0.1" % "test"' >> build.sbt


Other Links

http://skinny-framework.org/
http://scalikejdbc.org/
Java エンジニアチームが始めやすい Scala コーディングスタイル: https://www.slideshare.net/seratch/java-scala-ichigayageek