build.sbt

scalaVersion := "3.0.0-RC1"

MatchTypeSort.scala

import scala.compiletime.ops.int._

sealed trait HList {
  def ::[H](head: H): head.type :: this.type = new ::[head.type, this.type](head, this)
}
final case class ::[+H, +T <: HList](head: H, tail: T) extends HList
sealed trait HNil extends HList 
case object HNil extends HNil

object MatchTypeSort {
  type LTs[A <: HList, B <: Int] <: HList = A match {
    case HNil =>
      HNil
    case t :: ts =>
      (t < B) match {
        case true =>
          t :: LTs[ts, B]
        case false =>
          LTs[ts, B]
      }
  }

  type GTs[A <: HList, B <: Int] <: HList = A match {
    case HNil =>
      HNil
    case t :: ts =>
      (t > B) match {
        case true =>
          t :: GTs[ts, B]
        case false =>
          GTs[ts, B]
      }
    }

  def typed[A](a: A): Unit = ()

  type HListConcat[A <: HList, B <: HList] <: HList = A match {
    case HNil =>
      B
    case h :: t =>
      h :: (HListConcat[t, B])
  }

  type Sort[A <: HList] <: HList = A match {
    case HNil =>
      HNil
    case h :: t =>
      HListConcat[Sort[LTs[t, h]], h :: Sort[GTs[t, h]]]
  }

  def main(args: Array[String]): Unit = {
    typed[Sort[5 :: 3 :: 7 :: 2 :: 1 :: 6 :: 4 :: HNil]](
      1 :: 2 :: 3 :: 4 :: 5 :: 6 :: 7 :: (HNil: HNil)
    )
  }
}

plugins.sbt

addSbtPlugin("ch.epfl.lamp" % "sbt-dotty" % "0.5.3")