Scala 3：使用实验类型

Question

以下Scala 3代码以下文档效果很好

import scala.compiletime.ops.string.*
@main def refinedTypeInAction: Unit = 
  val hello: "hello " + "world" = "hello world"
  println(hello)

，但是，下面的一个

import scala.annotation.experimental
@experimental  
object UseExperimental:      
  def x: scala.compiletime.ops.string.Substring["hamburger", 4, 8] = "urge"

列出了编译时间错误，如下所示，

[error] -- [E008] Not Found Error: /Users/viswanath/projects/myproject/src/main/scala/RefinedType.scala:16:38 
[error] 16 |  def x: scala.compiletime.ops.string.Substring["hamburger", 4, 8] = "urge"
[error]    |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
[error]    |   type Substring is not a member of object scala.compiletime.ops.string
[error] one error found

我确实指的是 https://docs.scala-lang.org/scala3/reference/other-new-features/other-new-features/experiment-defs.html 但是我是努力克服汇编错误。请帮忙！