Question

我正在使用Scala进行学习我编写了这段代码来对列表中的元素进行排序

def isort(xs:List[Int]):List[Int]=
xs match{
 case List() => xs
 case y::ys => insert(y,isort(ys))
}
 def insert(x:Int,xs:List[Int]):List[Int]=
xs match{
 case List() => List(x)
case y::ys => if(x<y) x::xs else y :: insert(x,ys)

  }

但是我收到以下错误：

Constructor can not be instantiated to expected type found Scala.collection.Immutable required List[Int]
 in  
 `y::ys => insert(y,isort(ys))`

和我使用::

的类似错误

我参考教程：https://class.coursera.org/progfun-005/lecture

Answer 1

尝试使用REPL的粘贴模式。这将允许您在相同的上下文中定义两个def：

scala> :paste
// Entering paste mode (ctrl-D to finish)

def isort(xs:List[Int]):List[Int]=
xs match{
 case List() => xs
 case y::ys => insert(y,isort(ys))
}
 def insert(x:Int,xs:List[Int]):List[Int]=
xs match{
 case List() => List(x)
case y::ys => if(x<y) x::xs else y :: insert(x,ys)

  }

// Exiting paste mode, now interpreting.

isort: (xs: List[Int])List[Int]
insert: (x: Int, xs: List[Int])List[Int]

在scala中使用列表时发现错误

1 个答案: