如何在 scala shapeless 中显示 HList 的类型

Question

如何将列表的类型获取为字符串，以便打印它。例如 "Int :: Long :: String :: HNil"

val gen = Generic[?]
val typeString: String = ???
println("The type is " + typeString)

我知道字符串，如果它不是很有用，通常你想要 gen.Repr

中的类型

Answer 1

使用shapeless.Typeable:

scala> import shapeless._
import shapeless._

scala> case class A(i: Int, s: String)
defined class A

scala> val gen = Generic[A]
gen: shapeless.Generic[A]{type Repr =
  shapeless.::[Int,shapeless.::[String,shapeless.HNil]]} =
    anon$macro@56639061

scala> println(Typeable[gen.Repr].describe)
Int :: String :: HNil

如何在 scala shapeless 中显示 HList 的类型

how to show the type of a HList in scala shapeless

scala

shapeless