在 Scala 中是否可以在包中包含函数/方法{}？

Question

I am currently following Miss Wiem Zine's article (specifically on ZIO): Make your program testable

but I couldn't get pass the

package console {
  def println(line: String): ZIO[Console, Nothing, Unit] =
    ZIO.accessM(_.console println line)

  val readLine: ZIO[Console, Nothing, String] = 
    ZIO.accessM(_.console.readLine)
}

I've read in alvin alexander's page , but it's all about scoping.

I tried it in intellij, but it complains.

Could it be a

package object console {
...
}

instead of package console {} ?

Or is that a scala 3 thing? Or am I doing something wrong?

Answer 1

In Scala 2, we have a concept of package objects. There are examples here: https://www.scala-lang.org/docu/files/packageobjects/packageobjects.html .

I think code snippet from "Wiem Zine's article" is missing object keyword, so you are right it should be: package object console , since the whole example is on ZIO and Scala 2.x. There is no ZIO for Scala 3 yet, as far as I know:-)

@Thilo is also right that Scala 3 allows us to use top-level definitions right in the file without necessity to wrap into a block. Until Scala 3, one can use package object to get common package code.