Generic Show Derivation of Case Classes using Scala 3

CaseClassFun.scala

package io.chrisdavenport.shapelessless

import cats._
import cats.syntax.all._
import cats.effect._

import scala.deriving._
import scala.compiletime._
import org.tpolecat.typename._

// Primarily from learning from 
// https://github.com/scodec/scodec/blob/5e46cc8d85f8ad99bf65983f86f24076568a492c/shared/src/main/scala/scodec/Codec.scala#L633-L634

object Main extends IOApp:

  case class Foo(i: Int, b: String)
  import io.chrisdavenport.shapelessless.CaseClassFun.{_, given}
  

  def run(args: List[String]): IO[ExitCode] = {
    val foo = Foo(1, "bar")
    val x = summon[Show[Foo]]
    // IO(println("foo"))
    IO(println(show"$foo")) // Foo(i=1,b=bar)
      .as(ExitCode.Success)
  }

object CaseClassFun:

  private inline def encodeElems[A <: Tuple, L <: Tuple](a: Any, i: Int): String =
    inline erasedValue[A] match {
      case _: (hd *: EmptyTuple) => 
        inline erasedValue[L] match {
          case _ :(hdLabel *: tlLabels) => 
            val hdLabelValue = constValue[hdLabel].asInstanceOf[String]
            val show = summonInline[Show[hd]]
            hdLabelValue ++ "=" ++
            show.show(a.asInstanceOf[Product].productElement(i).asInstanceOf[hd])
          case EmptyTuple => sys.error("not possible - label for product not available")
        }
      case _: (hd *: tl) => 
        inline erasedValue[L] match {
          case _ :(hdLabel *: tlLabels) => 
            val hdLabelValue = constValue[hdLabel].asInstanceOf[String]
            val show = summonInline[Show[hd]]
            hdLabelValue ++ "=" ++
            show.show(a.asInstanceOf[Product].productElement(i).asInstanceOf[hd]) ++ "," ++
            encodeElems[tl, tlLabels](a, i + 1)
          case EmptyTuple => sys.error("not possible - label for product not available")
        }
      case EmptyTuple => ""
    }

  inline given [P <: Product](
    using 
    t: TypeName[P],
    m: Mirror.ProductOf[P],
  ) as Show[P] = 
    {(p: P) => 
      simpleTypeName(t.value) ++ "(" ++ 
      encodeElems[m.MirroredElemTypes, m.MirroredElemLabels](p, 0)
      ++ ")"
    }

  // scala.collection.immutable.List[scala.Option[scala.Int]] => List
  // io.chrisdavenport.shapelessless.Main.Foo => Foo
  def simpleTypeName(string: String): String = {
    val stop = string.indexOf("[")
    val topClass = 
      if (stop >= 0) string.substring(0, stop)
      else string
    val indexOfPeriodInTop = topClass.lastIndexOf(".")
    val simpleTopType = if (indexOfPeriodInTop >= 0) topClass.substring(indexOfPeriodInTop + 1, topClass.length)
      else topClass
    simpleTopType
  }