scala一些高级类型

package com.ming.test

import scala.collection.mutable.ArrayBuffer
import scala.io.Source
import java.awt.image.BufferedImage
import javax.imageio.ImageIO
import java.io.File

/**
 * 高级类型
 */
//单例类型，链式调用
class Document{
  def setTitle(title:String)={this}
  def setAuthor(author:String)={this}
}

class Book extends Document{
  def addBook(name:String):this.type={this}
}

//类型投影
class NetWork{
  class Member(val name:String){
    val contacts=new ArrayBuffer[Member]
  }
  private val members=new ArrayBuffer[Member]
  def join(name:String)={
    val m=new Member(name)
    members+=m
    m
  }
}

//定义Person类，两个泛型参数，分别是S，T,因此
//它是可以用中置表达式进行变量定义的
case class Person[S,T](val name:S,val age:T)
//中置类型-中置类型是代表带有两个参数的类型
class ZhongziType{
  //下面的代码是一种中置表达方法，相当于
  //val p:Person[String,Int]
  val p:String Person Int= Person("摇摆少年梦",18)
}

//抽象类型--类或特质可以定义一个在子类中被具体化的抽象类型
trait Reader{
  type Contents
  def read(fileName : String):Contents
}

trait Reade1r[T]{
   def read(fileName : String):T
}

//类型Contents是抽象的。具体的子类需要指定这个类型
class StringReader extends Reader{
  type Contents=String
   def read(fileName : String)=Source.fromFile(fileName,"UTF-8").mkString
}

class ImageReader extends Reader{
  type Contents=BufferedImage
  def read(fileName :String)=ImageIO.read(new File(fileName))
}

//

object SeniorTypeTest {

  def main(args: Array[String]): Unit = {
    var d=new Book
    var s=d.setAuthor("a").setTitle("hello");
    println(s)
    var b=new Book
    b.addBook("<<helloworld>>").setAuthor("mingge").setTitle("hello")
    println(b)
  }
}

感觉scala好多规则，好晕好绕。。。