Scala深入浅出进阶经典 第87讲：Scala中使用For表达式做查询

package com.dt.scalaInAction.demo_087/** * Scala中使用For表达式做查询 */case class Book(title: String, author: List[String])object For_Query {    def main(args: Array[String]): Unit = {        val books = List(            Book("Structure and Interpretation", List("Abelson,Harold", "Sussman")),            Book("Principles of Compiler Design", List("Aho,Alfred", "Ullman,Jeffery")),            Book("Programming in Modula-2", List("Wirth,Niklaus")),            Book("Introduction to Functional Programming", List("Bird,Richard")),            Book("The Java Language Specification", List("Gosling,James", "Joy,Bill", "Steele,Guy", "Bracha,Gilad"))        )                val result = for(b <-books; a<-b.author; if a startsWith "Gosling") yield b.title        println(result)  //result: List(The Java Language Specification)                val result1 = for(b <-books; if(b.title indexOf "Programming")!= -1 ) yield b.title        println(result1)  //result: List(Programming in Modula-2, Introduction to Functional Programming)    }}