scala Stream中的#::运算符是什么？

Question

可能重复:
在Scala文档中搜索#::

我正在浏览Stream的文档

filter方法有以下代码:

def naturalsFrom(i: Int): Stream[Int] = i #:: naturalsFrom(i + 1)
naturalsFrom(1)  10 } filter { _ % 5 == 0 } take 10 mkString(", ")

什么是#::运算符？这是否映射到某个函数调用？

Answer 1

x #:: xs

回报

Stream.cons(x, xs)

返回元素x的Stream,后跟Stream xs.

Answer 2

正如SHildebrandt所说,#::是Streams的合规运营商.

换句话说,#::是要将:: is to to Lists

val x = Stream(1,2,3,4)                   //> x  : scala.collection.immutable.Stream[Int] = Stream(1, ?)
10#::x                                    //> res0: scala.collection.immutable.Stream[Int] = Stream(10, ?)

val y = List(1,2,3,4)                     //> y  : List[Int] = List(1, 2, 3, 4)
10::y                                     //> res1: List[Int] = List(10, 1, 2, 3, 4)