scala学习笔记：理解stream和view

先来个正常的：

scala> (0 to 5).map((x:Int)=>{println(x);x*2}).foreach(println)
0
1
2
3
4
5
0
2
4
6
8
10

再来个stream版的：

scala> (0 to 5).toStream.map((x:Int)=>{println(x);x*2}).foreach(println)
0
0
1
2
2
4
3
6
4
8
5
10

最后来个view版的：

scala> (0 to 5).view.map((x:Int)=>{println(x);x*2}).foreach(println)
0
0
1
2
2
4
3
6
4
8
5
10

目前看，view和stream的表现一样，那么区别何在呢？观察下一个：

scala> (0 to 5).toStream.map((x:Int)=>{println(x);x*2})
0
res5: scala.collection.immutable.Stream[Int] = Stream(0, ?)

scala> (0 to 5).view.map((x:Int)=>{println(x);x*2})
res6: scala.collection.SeqView[Int,Seq[_]] = SeqViewM(...)

看来stream会优先求第一个值的！这就是区别的全部么？