Scala 3 - Trie

Trie.scala

import scala.io.{Source, StdIn}

object Main {
  type Trie[A] = A match {
    case Nothing => Map[A, Nothing]
    case A => Map[A, Trie[A]]
    }

  def toTrie(names: List[String]): Trie[Char] =
    names.filterNot(_.isEmpty)
         .groupBy(_.head)
         .view
         .mapValues(x => toTrie(x.map(_.tail)))
         .toMap

  extension (self: Trie[Char]) {
    def search(keyword: List[Char]): Boolean = keyword match {
      case Nil => true
      case h :: t => self match {
        case map: Map[Char, Trie[Char]] if map.contains(h) => map(h).search(t)
        case _ => false
      }
    }

    def insert(keyword: List[Char]): Trie[Char] = keyword match {
      case Nil => self
      case h :: t => self match {
        case map: Map[Char, Trie[Char]] if map.contains(h) =>
          map.updated(h, map(h).insert(t))
        case map: Map[Char, Trie[Char]] =>
          map.updated(h, toTrie(List(t.mkString(""))))
      }
    }
    
    def isEmpty: Boolean = self == Map()

    def delete(keyword: List[Char]): Trie[Char] = keyword match {
      case Nil => self
      case h :: t => self match {
        case map: Map[Char, Trie[Char]] if map.contains(h) && map(h).isEmpty => map.removed(h)
        case map: Map[Char, Trie[Char]] if map.contains(h) =>
          val deleted = map(h).delete(t)
          if (deleted.isEmpty) {
            map.removed(h)
          } else {
            map.updated(h, deleted)
          }
        case map: Map[Char, Trie[Char]] =>
          println("doing nothing")
          self
      }
    }
  }

  def main(args: Array[String]): Unit = {
    val words = List()
    val trie = toTrie(words)
    println(trie)
    var nextTrie = trie
    val deleteCommand = "del (.+)".r
    while (true) {
      print("> ")
      StdIn.readLine() match {
        case "" =>
          println("Can't be empty string")
        case "quit" =>
          println("Finish")
          System.exit(1)
        case "print" =>
          println(nextTrie)
        case deleteCommand(str) =>
          nextTrie = nextTrie.delete(str.toList)
        case str if nextTrie.search(str.toList) =>
          println("Found words")
        case str =>
          println("No word found, try next time")
          nextTrie = nextTrie.insert(str.toList)
      }

      System.out.flush()
    }
  }

  def msg = "I was compiled by dotty :)"
}