scala函数文字中的`=>`

Question

What does the second => mean in the following function literal ?

val result: () => Int = () => throw new RuntimeException
result: () => Int = <function0>

Answer 1

In type declaration val result: () => Int it is just an easy way to declare a function type:

() => Int is the same as Function0[Int]

Here () => throw new RuntimeException it's a function declaration and => separates arguments from body. Therefore it's declaration of an anonymous function with no arguments and body throw new RuntimeException . It's equivalent to:

def f() = throw new RuntimeException

Answer 2

First => means that type of val is function which apply no parameters and return Int .

Second => is divider between parameter list () and function's body throw new RuntimeException