Regarding :: there is another Stackoverflow entry which covers the :: case. In short, it is used to construct Lists by 'consing' a head element and a tail list. It is both a class which represents a cons'ed list and which can be used as an extractor, but most commonly it is a method on a list. As Pablo Fernandez points out, since it ends in a colon, it is right associative, meaning the receiver of the method call is to the right, and the argument to the left of the operator. That way you can elegantly express the consing as prepending a new head element to an existing list:

val x = 2 :: 3 :: Nil  // same result as List(2, 3)
val y = 1 :: x         // yields List(1, 2, 3)

这相当于

val x = Nil.::(3).::(2) // successively prepend 3 and 2 to an empty list
val y = x.::(1)         // then prepend 1

作为提取器对象的用法如下:

def extract(l: List[Int]) = l match {
   case Nil          => "empty"
   case head :: Nil  => "exactly one element (" + head + ")"
   case head :: tail => "more than one element"
}

extract(Nil)          // yields "empty"
extract(List(1))      // yields "exactly one element (1)"
extract(List(2, 3))   // yields "more than one element"

这看起来像一个运算符，但它实际上只是另一种(更可读的)书写方式

def extract2(l: List[Int]) = l match {
   case Nil            => "empty"
   case ::(head, Nil)  => "exactly one element (" + head + ")"
   case ::(head, tail) => "more than one element"
}

你可以在这篇文章中阅读更多关于提取器的信息。

作为Daniel和0__精彩回答的补充，我不得不说Scala理解某些符号的Unicode类比，所以代替

for (n <- 1 to 10) n % 2 match {
  case 0 => println("even")
  case 1 => println("odd")
}

你可以这样写

for (n ← 1 to 10) n % 2 match {
  case 0 ⇒ println("even")
  case 1 ⇒ println("odd")
}

只是为其他精彩的答案锦上添花。Scala提供了两个经常被批评的符号操作符，/:(foldLeft)和:\ (foldRight)操作符，第一个是右关联操作符。所以下面三个语句是等价的:

( 1 to 100 ).foldLeft( 0, _+_ )
( 1 to 100 )./:( 0 )( _+_ )
( 0 /: ( 1 to 100 ) )( _+_ )

就像下面这三个:

( 1 to 100 ).foldRight( 0, _+_ )
( 1 to 100 ).:\( 0 )( _+_ )
( ( 1 to 100 ) :\ 0 )( _+_ )

我认为现代IDE对于理解大型scala项目至关重要。由于这些操作符也是方法，在intellij思想中，我只是控制-单击或控制-b进入定义。

你可以右键点击一个cons操作符(::)，然后在scala javadoc中说“在这个列表的开头添加一个元素”。在用户定义的操作符中，这一点变得更加关键，因为它们可能被定义为很难找到的隐式…你的IDE知道隐式的定义在哪里。

Regarding :: there is another Stackoverflow entry which covers the :: case. In short, it is used to construct Lists by 'consing' a head element and a tail list. It is both a class which represents a cons'ed list and which can be used as an extractor, but most commonly it is a method on a list. As Pablo Fernandez points out, since it ends in a colon, it is right associative, meaning the receiver of the method call is to the right, and the argument to the left of the operator. That way you can elegantly express the consing as prepending a new head element to an existing list:

val x = 2 :: 3 :: Nil  // same result as List(2, 3)
val y = 1 :: x         // yields List(1, 2, 3)

这相当于

val x = Nil.::(3).::(2) // successively prepend 3 and 2 to an empty list
val y = x.::(1)         // then prepend 1

作为提取器对象的用法如下:

def extract(l: List[Int]) = l match {
   case Nil          => "empty"
   case head :: Nil  => "exactly one element (" + head + ")"
   case head :: tail => "more than one element"
}

extract(Nil)          // yields "empty"
extract(List(1))      // yields "exactly one element (1)"
extract(List(2, 3))   // yields "more than one element"

这看起来像一个运算符，但它实际上只是另一种(更可读的)书写方式

def extract2(l: List[Int]) = l match {
   case Nil            => "empty"
   case ::(head, Nil)  => "exactly one element (" + head + ")"
   case ::(head, tail) => "more than one element"
}

你可以在这篇文章中阅读更多关于提取器的信息。

Scala和其他语言的一个(在我看来是好的)区别是，它允许你用几乎任何字符来命名你的方法。

您列举的不是“标点符号”，而是简单明了的方法，因此它们的行为因对象而异(尽管存在一些约定)。

例如，查看Scaladoc文档中的List，您将看到这里提到的一些方法。

请记住以下几点:

大多数情况下，A操作符+= B组合转换为A = A操作符B，如||=或++=示例。 以:结尾的方法是右结合的，这意味着A:: B实际上是B.::(A)。

您可以通过浏览Scala文档找到大部分答案。在这里保留一个参考将重复工作，并且它将很快落后:)