如何编写一个在scala中通过任意数字（Ordering [_]）通用的方法？

问题描述

我试图实现一个可应用于任何数字的简单方法：

  
 
 
调用上述（或者我用 _  c $ c>）给了我以下错误： 
 
 
  error：type mismatch; 
 found：Int（3）
 required：Ordering [_] 
 NumberUtils.bucketise（List（1,2,3），3）
  
 
什么是我想要达到的正确语法？  
解决方案 
 
 
  def bucketise [A]（存储桶：Seq [A ]，候选人：A）（隐式ev：排序[A]）：A = ??? 
  
可以以加糖形式写入： 
 
 
  def bucketise [A：排序]（桶：Seq [A]，候选人：A）：A = ??? 
  
 
I'm trying to implement a simple method that can be applied to any number:
/**
 * Round `candidate` to the nearest `bucket` value.
 */
def bucketise[Ordering[A]](buckets: Seq[Ordering[A]], 
    candidate: Ordering[A]): Ordering[A] = ???
I don't want just parameterise totally generically since my method will use < and > comparisons. I think that means I should restrict to any Ordering[_] type, but I don't seem to be able to specify that. 
Calling the above (or the variation where I replace A with _) gives me the following error:
error: type mismatch;
 found   : Int(3)
 required: Ordering[_]
       NumberUtils.bucketise(List(1,2,3), 3)
What's the right syntax for what I'm trying to achieve?
 解决方案 
Unless I misunderstand, what you want is:
def bucketise[A](buckets: Seq[A], candidate: A)(implicit ev: Ordering[A]): A = ???
which can be written in the sugared form:
def bucketise[A : Ordering](buckets: Seq[A], candidate: A): A = ???
                        
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