import reflect.runtime.universe._

trait AST[T] {
  def tpe: Type
}

case class ASTVal[T: WeakTypeTag](value: T) extends AST[T] {
  def tpe = implicitly[WeakTypeTag[T]].tpe
}

abstract class ASTTypeMatch[T: WeakTypeTag] {
  def unapply(v: AST[_]) = v.tpe =:= implicitly[WeakTypeTag[T]].tpe
}

object isLong extends ASTTypeMatch[Long]
object isDouble extends ASTTypeMatch[Double]
// etc ...

object Test {
  def test[T](ast: AST[T]) = ast match {
    case a @ isLong() => //do something with a: AST[Long]
  }
}