为什么eta-expansion不适用于隐式添加的成员 [英] Why eta-expansion doesn't work with implicitly added members

问题描述

这不起作用：

 ％ -  10s％-50s％s.format _ 
 < console>：13：错误：特性字符串类型中缺少方法格式的参数; 
如果您想将其视为部分应用函数，则使用`_'后跟此方法
％-10s％-50s％s.format _ 
  
 
 
 
但是这样做： 
 
 
  import scala.collection .immutable._ 
 
 scala> （％-10s％-50s％s：StringLike [_]）。format _ 
 res91：Seq [Any] => String =< function1> 
  
那么，为什么我必须明确指定类型类？ 
 
 
 
 
    / browse / SI-8299rel =nofollow> https://issues.scala-lang.org/browse/SI-8299  
 
 
 
这就是不是一个完整的原因。
 
 
 
不确定这是否需要说明，但：
 
 
 阶> val f：Seq [Any] => String =％-10s％-50s％s.format 
 f：Seq [Any] => String =< function1> 
  
 
This doesn't work:
"%-10s %-50s %s".format _
<console>:13: error: missing arguments for method format in trait StringLike;
 follow this method with `_' if you want to treat it as a partially applied function
          "%-10s %-50s %s".format _
But this works:
import scala.collection.immutable._

scala> ("%-10s %-50s %s": StringLike[_]).format _
res91: Seq[Any] => String = <function1>
So, why i have to specify type class explicitly?
解决方案
This is why:

https://issues.scala-lang.org/browse/SI-8299

That's not a whole lotta why.

Not sure if this needs saying, but:
scala> val f: Seq[Any] => String = "%-10s %-50s %s".format
f: Seq[Any] => String = <function1>


                        
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