proxies.scala

package proxy
import language.dynamics

abstract class Param[T] { type Type }

object Param {
  def apply[T](name: String) = new Param[name.type] { type Type = T }
}

class Proxy(underlying: Map[String, Any]) extends Dynamic {
  def selectDynamic[T](name: String)(implicit param: Param[name.type]): param.Type =
    underlying(name).asInstanceOf[param.Type]
}

object Test {
  val proxy = new Proxy(Map("foo" -> "Hello world", "bar" -> 42, "baz" -> 'xyz))
  implicit def foo = Param[String]("foo")
  implicit def bar = Param[Int]("bar")
  implicit def baz = Param[Symbol]("baz")

  println(proxy.foo)
  println(proxy.bar)
  println(proxy.baz)
}