Created
June 20, 2016 17:01
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| case class Foo(bar: String, baz: Int, quux: Boolean) | |
| import shapeless._, labelled.FieldType, record._ | |
| trait ToLabels[L <: HList] { | |
| def apply(l: L): List[String] | |
| } | |
| trait LowPriorityToLabels { | |
| implicit def hconsToLabels[K <: Symbol, V, T <: HList](implicit | |
| wit: Witness.Aux[K], | |
| toLabels: ToLabels[T] | |
| ): ToLabels[FieldType[K, V] :: T] = new ToLabels[FieldType[K, V] :: T] { | |
| def apply(l: FieldType[K, V] :: T): List[String] = | |
| List(wit.value.name) ++ toLabels(l.tail) | |
| } | |
| } | |
| object ToLabels extends LowPriorityToLabels { | |
| implicit val hnilToLabels: ToLabels[HNil] = new ToLabels[HNil] { | |
| def apply(l: HNil): List[String] = Nil | |
| } | |
| implicit def hconsToLabels0[K <: Symbol, V, R <: HList, T <: HList](implicit | |
| wit: Witness.Aux[K], | |
| gen: LabelledGeneric.Aux[V, R], | |
| toLabelsR: ToLabels[R], | |
| toLabelsT: ToLabels[T] | |
| ): ToLabels[FieldType[K, V] :: T] = new ToLabels[FieldType[K, V] :: T] { | |
| def apply(l: FieldType[K, V] :: T): List[String] = | |
| List(wit.value.name) ++ toLabelsT(l.tail) | |
| } | |
| } | |
| implicit class ToLabelOps[A](val a: A) extends AnyVal { | |
| def toLabels[L <: HList](implicit | |
| gen: LabelledGeneric.Aux[A, L], | |
| tmr: ToLabels[L] | |
| ): List[String] = tmr(gen.to(a)) | |
| } | |
| println(Foo("s",1,true).toLabels) |
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