kind.scala

// Updated for Scala 2.10.0.
def kind[A: scala.reflect.runtime.universe.TypeTag](a: A): String = {
  import scala.reflect.runtime.universe._
  def typeKind(sig: Type): String = sig match {
    case PolyType(params, resultType) =>
      (params map { p =>
        typeKind(p.typeSignature) match {
          case "*" => "*"
          case s   => "(" + s + ")"
        }
      }).mkString(" -> ") + " -> *"
    case _ => "*"
  }
  def typeSig(tpe: Type): Type = tpe match {
    case SingleType(pre, sym) => sym.companionSymbol.typeSignature
    case ExistentialType(q, TypeRef(pre, sym, args)) => sym.typeSignature
    case TypeRef(pre, sym, args) => sym.typeSignature
  }
  val sig = typeSig(typeOf[A])
  val s = typeKind(sig)
  sig.typeSymbol.name + "'s kind is " + s + ". " + (s match {
    case "*" =>
      "This is a proper type."
    case x if !(x contains "(") =>
      "This is a type constructor: a 1st-order-kinded type."
    case x =>
      "This is a type constructor that takes type constructor(s): a higher-kinded type."
  })
}

/*
scala> kind[Int]
res72: String = Int's kind is *. This is a proper type.
scala> kind[Option.type]
res73: String = Option's kind is * -> *. This is a type constructor: a 1st-order-kinded type.
scala> kind[Functor.type]
res74: String = Functor's kind is (* -> *) -> *. This is a type constructor that takes type constructor(s): a higher-kinded type.
*/