Scala的map高阶函数应用

scala> val c =List("x","y","z")

c:List[String]=List(x, y, z)

scala> c.map(x => x.toUpperCase)

res7:List[String]=List(X, Y, Z)

scala> c.map(_.toUpperCase)

res8:List[String]=List(X, Y, Z)

scala> l.filter(_%2==1)

res10:List[Int]=List(1,3)

scala> l.filter(_%2==1).map(_+10)

res11:List[Int]=List(11,13)

scala> val q=List(l,List(4,5,6))

q:List[List[Int]]=List(List(1,2,3),List(4,5,6))

scala> q.map(x=>x.filter(_%2==0))

res12:List[List[Int]]=List(List(2),List(4,6))

scala> q.map(_.filter(_%2==0))

res13:List[List[Int]]=List(List(2),List(4,6))

scala> q.flatMap(_.filter(_%2==0))

res15:List[Int]=List(2,4,6)