匿名函数的scala列表

Question

Like to create a list of function literals and (a) avoid pre-defining them and (b) use shorthand syntax. Failing at the moment.

def g = (x: Int) => x + 1 //pre-defined

def h = (x: Int) => x + 2

List(g,h) //succeeds

List( (x: Int) => x + 1, (x: Int) => x + 2) ) //fails
      ^';' expected but ')' found.

Answer 1

Please clarify, do you know types of your functions in advance?

If yes, then you can explicitly specify type of your list:

@ List[Int=>Int](x => x + 1, x => x + 2)

res20: List[Int => Int] = List(<function1>, <function1>)

Or even shorter:

@ List[Int=>Int](_ + 1, _ + 2)

res21: List[Int => Int] = List(<function1>, <function1>)

If you want List type to be inferred, try following syntax:

@ List({ x: Int => x + 1}, { x: Int => x + 2 })
res22: List[Int => Int] = List(<function1>, <function1>)