Console Effect handler

Console.kt

import arrow.core.continuations.EffectScope
import arrow.core.continuations.effect

object EndOfLine

interface Console {
  context(EffectScope<EndOfLine>)
  suspend fun read(): String

  suspend fun String.write(): Unit
  suspend fun String.writeLine(): Unit

  companion object Default : Console {
    context(EffectScope<EndOfLine>)
      override suspend fun read(): String = readlnOrNull() ?: shift(EndOfLine)

    override suspend fun String.write() = print(this)
    override suspend fun String.writeLine() = println(this)
  }
}

context(Console, EffectScope<EndOfLine>, EffectScope<String>)
  tailrec suspend fun program(): Unit {
  "what is your name?".writeLine()
  val res = read()
  return if (res.isBlank()) {
    "empty name".writeLine()
    program()
  } else if (res == "me") {
    "wrong name!".writeLine()
    shift("wrong name")
  } else println("Hello $res")
}

suspend fun main() {
  with(Console.Default) {
    effect<String, Unit> {
      effect<EndOfLine, Unit> {
        program()
      }.fold({ println(it) }, { println(it) })
    }.fold({ println(it) }, { println(it) })
  }
}