scala macro how to infer implicit CanBuildFrom

Question

val cbfType =
          appliedType(
            typeOf[collection.generic.CanBuildFrom[_, _, _]].typeConstructor,
            typeOf[List[_]].typeConstructor :: typeOf[String] :: typeOf[List[String]] :: Nil
          )
        println(cbfType)
        val cbf = c.inferImplicitValue(cbfType)
        println(cbf)

I am trying to infer an implicit CanBuildFrom .

But the cbf I got is empty tree ?

How can I get the implicit instance of CanBuildFrom in a scala macro?

Answer 1

您需要编写typeOf[List[_]]而不是typeOf[List[_]].typeConstructor ： https : typeOf[List[_]].typeConstructor 。