8. High-order function

Common functions

Higher order functions: parameters or return values are functions

Object A_ Base {  = {    println (Mymax (1,2, Math.max))    println (Myadd ( 1) (2))  }   = ={//f Type of mapping is function    f (A, B)  }  def myadd (a:int)={//return value type is a function, inner _ represents the function itself    def inner (b:int)={      + b    }    inner _  }}

anonymous functions

Scala> Arr.map ((i:int) = i*2= Array (24) Scala> Arr.map ((i:int ) = = i*2= Array (24)

Scala> Arr.map ((i) = i*2= Array (24) Scala> arr.map (i = > i*2= Array (24)

Scala> Arr.map (_*2= Array (24)

Currying

Definition: The process of turning a function that accepts two parameters into a new function that takes a parameter. That is, the function after the curry returns the function with the second argument as the argument.

Scala> def Add (a:int,b:int) =a+b//original function add: (A:int, B:int) Int^Scala> Def add (a:int) ={b:int = A += Intscala> Add (1) (23Scala> Def add (a:i NT) (b:int) =a + b//Curry simplified add: (a:int) (b:int) Intscala> Add (3) (47 

Benefit: Take a parameter out alone to provide more information for type inference

Control abstraction

In Scala, a series of statements can be composed of functions with no parameters and no return value

Object C_ Control Abstract {  = {    runinthread (println (Thread.CurrentThread (). GetName ()))    Runinthread (println (Thread.CurrentThread (). GetName ()))  }   = unit): unit ={    new  Thread () {      override def run (): unit ={        block      }    }. Start ()  }}

8. High-order function