第88讲：Scala中使用For表达式实现map、flatMap、filter

第88讲：Scala中使用For表达式实现map、flatMap、filter

object For_Advanced {

  def main(args: Array[String]) {}
 
  def map[A, B](list: List[A], f: A => B): List[B] =
    for(element <- list) yield f(element)
  def flatMap[A, B](list: List[A], f: A => List[B]): List[B] =
    for(x <- list; y <- f(x)) yield y
  def filter[A](list: List[A], f: A => Boolean): List[A] =
    for(elem <- list if f(elem)) yield elem
}

 

 

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