查看 scala 版本
scala -version
Scala code runner version 2.12.8 — Copyright 2002-2018, LAMP/EPFL and Lightbend, Inc.
运行 scala，进入交互式界面
➜ ~ scala
Welcome to Scala 2.12.8 (Java HotSpot(TM) 64-Bit Server VM, Java 9.0.4).
Type in expressions for evaluation. Or try :help.
// 输出 hell oworld
println(“Hello World”)
// 输出
//scala> println(“hello world”)
//hello world