从 Mirror 获取 MirroredElemLabels

Question

Scala 3 的 scala.deriving.Mirror 有一个类型成员 MirroredElemLabels，它是一个字符串文字元组。将该类型作为值的标准方法是什么？

编辑：here's the code 尝试使用 summonAll

时会产生编译器错误

case class Test(a: Int, b: String)
val mirror = implicitly[Mirror.ProductOf[Test]]
val labels = summonAll[mirror.MirroredElemLabels]
println(labels)

cannot reduce inline match with
 scrutinee:  compiletime.erasedValue[App.mirror.MirroredElemLabels] : App.mirror.MirroredElemLabels
 patterns :  case _:EmptyTuple
             case _:*:[t @ _, ts @ _]

Answer 1

尝试使用scala.ValueOf

case class A(i: Int, s: String)

import scala.deriving.Mirror
import scala.compiletime.summonAll

val mirror = summon[Mirror.Of[A]]    
type ValueOfs = Tuple.Map[mirror.MirroredElemLabels, ValueOf]
val valueOfs = summonAll[ValueOfs]

def values(t: Tuple): Tuple = t match
  case (h: ValueOf[_]) *: t1 => h.value *: values(t1)
  case EmptyTuple => EmptyTuple

values(valueOfs) // (i,s)

http://dotty.epfl.ch/docs/reference/contextual/derivation.html

从 Mirror 获取 MirroredElemLabels

Getting MirroredElemLabels from Mirror

scala

generics

shapeless

type-level-computation

scala-3