Extremely slow parsing

[vigoo]

As we discovered on Zymposium on 22th of April, this example:

import zio.Chunk
import zio.parser._
import zio.parser.internal.Debug

object Example extends App {


  case class ChessCoord(row: Char, col: Byte)
  case class ChessMove(from: ChessCoord, to: ChessCoord)

  val chessCoord =
    (Syntax.charIn("ABCDEFGH") ~ Syntax.digit.transform(
      _.toString.toByte,
      (byte: Byte) => byte.toString.head
    )).transform(
      { case (r, c) => ChessCoord(r, c) },
      (cc: ChessCoord) => (cc.row, cc.col)
    )

  val whitespaces = Syntax.whitespace.repeat.unit(Chunk(' '))

  val chessMove =
    (chessCoord ~ whitespaces ~ Syntax.string("->", ()) ~ whitespaces ~ chessCoord).transform(
      { case (from ,to) => ChessMove(from, to) },
      (cm: ChessMove) => (cm.from, cm.to)
    )

  Debug.printParserTree(chessMove.asParser.optimized)

  val parsed = chessMove.parseString("""E1  -> A4""")
  val printed = chessMove.printString(parsed.toOption.get)

  println(parsed)
  println(printed)
}

runs very slowly.