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Scala函数定义和用法(Scala function definitions and usage)

 基于以下定义函数的示例，在不同场景中2和3的最佳用途是什么？  
 
  def sum(x: Int, y: Int): Int = { x+y }这是一个带参数，返回类型和函数体的函数定义  
  val sum = (x: Int, y: Int) => { x+y }这看起来像是一个lambda函数赋值给变量，为什么返回类型永远不会在这里定义？  
  val sum: (Int, Int) => Int = (x,y) => { x+y }这是将函数定义为一个类型？ 我不明白这是怎么回事！  
 
 调用时所有3个函数将产生相同的结果：  
 scala> sum(1,2) Int = 3 

Based on below examples of defining functions what is the best use of 2 and 3 in different scenarios? 
 
 def sum(x: Int, y: Int): Int = { x+y } This is a function definition with arguments, return type and function body 
 val sum = (x: Int, y: Int) => { x+y } This seems like an assignment of lambda function to a variable, why return type is never defined here? 
 val sum: (Int, Int) => Int = (x,y) => { x+y } This is defining a function as a type? I don't understand how this works! 
 
All 3 functions when invoked will yield the same result: 
scala> sum(1,2) Int = 3

原文：https://stackoverflow.com/questions/22747631

更新时间：2021-10-13 22:10

最满意答案

 我假设你正在使用Python 3.在Python 2中，字符串默认是字节，所以它只会适合你。 但在Python 3中，字符串是unicode并且被解释为unicode，如果您将字节字符串读为unicode，则会导致此问题更难。  
 这个解决方案受到了mgilson的回答的启发。 我们可以通过使用literal_eval从字面上评估您的unicode字符串为字节字符串：  
from ast import literal_eval

with open('source.txt', 'r', encoding='utf-8') as f_open:
    source = f_open.read()
    string = literal_eval("b'{}'".format(source)).decode('utf-8')
    print(string)  # 扎加拉

I'm assuming you're using Python 3. In Python 2, strings are bytes by default, so it would just work for you. But in Python 3, strings are unicode and interpretted as unicode, which is what makes this problem harder if you have a byte string being read as unicode. 
This solution was inspired by mgilson's answer. We can literally evaluate your unicode string as a byte string by using literal_eval: 
from ast import literal_eval

with open('source.txt', 'r', encoding='utf-8') as f_open:
    source = f_open.read()
    string = literal_eval("b'{}'".format(source)).decode('utf-8')
    print(string)  # 扎加拉

Scala函数定义和用法(Scala function definitions and usage)

最满意答案

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