Scala 3中的fusemap宏

Question

遵循元编程教程在这里fusemap示例可以使用。我拥有的宏是（在宏中对象）

  def fuseMap[T: Type](x: Expr[List[T]])(using Quotes): Expr[List[T]] =
    println("Initial passed in x: " + x.show)
    x match {
      case '{
            type u
            type v
            ($ls: List[`u`])
              .map($f: `u` => `v`)
              .map($g: `v` => T)
          } =>
        '{ $ls.map(y => $g($f(y))) }
        val result = '{ $ls.map(y => $g($f(y))) }

        println(result.show)
        result
      case _ =>
        println("fuseMap didn't do anything")
        x
    }

  inline def simplify[T](x: List[T]): List[T] = ${ fuseMap('x) }

，并像我期望看到在Compile上打印出的简化代码一样在单独的文件中调用

object macrofun extends App {

  val l = List(1, 2, 3)
  val f = (x: Int) => x + 1
  val g = (y: Int) => y * 2

  val r = simplify {
    List(1, 2, 3)
      .map(f)
      .map(g)
  }

  println(s"Result of l is $r")

}

，但是我看到“ Fusemap无需任何事情”。

Answer 1

我能够通过将论点提交简化内联来获得这项工作

inline def simplify[T](inline x: List[T]): List[T] = ${ fuseMap('x) }