scala3 feature examples - tree as typed enums / published by https://github.com/dacr/code-examples-manager #84bba0cf-f501-4e42-80bd-6d05ebe1e8f8/6c8b0126038d97bb63e6681f93a3e2f343cac6a4

scala3-feature-enums-typed.scala

// summary : scala3 feature examples - tree as typed enums
// keywords : scala3, tutorial, @testable
// publish : gist
// authors : David Crosson
// license : Apache NON-AI License Version 2.0 (https://raw.githubusercontent.com/non-ai-licenses/non-ai-licenses/main/NON-AI-APACHE2)
// id : 84bba0cf-f501-4e42-80bd-6d05ebe1e8f8
// created-on : 2021-03-23T17:18:13+01:00
// managed-by : https://github.com/dacr/code-examples-manager
// run-with : scala-cli $file

//> using scala "3.1.1"

enum Tree[T]:
  case Node(children: List[Tree[T]])
  case Leaf(content: T)

  def map[U](f: T => U): Tree[U] =
    def convert(tree: Tree[T]): Tree[U] =
      tree match
        case Leaf(content) => Leaf(f(content))
        case Node(children) => Node(children.map(convert))
    convert(this)

@main def run():Unit =
  import Tree.{Node,Leaf}
  val tree = Node(Node(Leaf(1)::Leaf(2)::Nil)::Leaf(3)::Nil)
  println(tree)