Scala 下划线 - 错误：扩展函数缺少参数类型
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Scala underscore - ERROR: missing parameter type for expanded function
提问by Jeff Storey
I know there have been quite a few questions on this, but I've created a simple example that I thought should work,but still does not and I'm not sure I understand why
我知道对此有很多问题，但是我创建了一个我认为应该可行的简单示例，但仍然没有，我不确定我明白为什么
val myStrings = new Array[String](3)
// do some string initialization
// this works
myStrings.foreach(println(_))
// ERROR: missing parameter type for expanded function
myStrings.foreach(println(_.toString))
Can someone explain why the second statement does not compile?
有人可以解释为什么第二个语句不能编译吗？
回答by retronym
It expands to:
它扩展为：
myStrings.foreach(println(x => x.toString))
You want:
你要：
myStrings.foreach(x => println(x.toString))
The placeholder syntax for anonymous functions replaces the smallest possible containing expression with a function.
匿名函数的占位符语法用函数替换了尽可能小的包含表达式。
