A simple example for Scala 3 type class derivation:

	import scala.deriving.Mirror.ProductOf
	object Decoder {
	type Row = List[String]
	extension (row: Row)
	def as[T](using p: ProductOf[T], d: RowDecoder[p.MirroredElemTypes]): T =
	p.fromProduct(d.decode(row))
	trait RowDecoder[A]:
	def decode(a: Decoder.Row): A
	trait FieldDecoder[A]:
	def decodeField(a: String): A
	private def csvToProduct[P](row: Row)(using p: ProductOf[P], d: RowDecoder[p.MirroredElemTypes]): P = row.as[P]
	given RowDecoder[EmptyTuple] with
	def decode(a: Row): EmptyTuple = EmptyTuple
	given FieldDecoder[Int] with
	def decodeField(x: String): Int = x.toInt
	given FieldDecoder[Boolean] with
	def decodeField(x: String): Boolean = x.toBoolean
	given FieldDecoder[String] with
	def decodeField(x: String): String = x
	given FieldDecoder[BigDecimal] with
	def decodeField(x: String): BigDecimal = BigDecimal(x)
	given FieldDecoder[Double] with
	def decodeField(x: String): Double = x.toDouble
	given decodeLine[H: FieldDecoder, T <: Tuple : RowDecoder]: RowDecoder[H *: T] with
	def decode(row: Row): H *: T = {
	val line = if (row.nonEmpty) row else List("")
	summon[FieldDecoder[H]].decodeField(line.head)
	*:
	summon[RowDecoder[T]].decode(line.tail)
	}
	def main(args: Array[String]): Unit = {
	case class Foo(i: Int, b: Boolean, s: String)
	import Decoder.*
	val foo = csvToProduct[Foo](List("42", "true", "Hello"))
	//val sp500 = csvToProduct[Sp500Divdend](List("1900.01", "6.10", "0.22"))
	println(foo)
	}
	}

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