not found value ~ in Scala

I am defining some paths but then i run into this error for the tilde ~ right before " pathPrefix(start)" . I am a bit new in Scala and so something do not click right away. thanks

 not found:value ~ 

Is it because i need to define a function? If so why?

import   
  akka.http.scaladsl.marshallers.xml.ScalaXmlSupport.defaultNodeSeqMarshaller
    import akka.http.scaladsl.server.{ HttpApp, Route }
    import akka.http.scaladsl.model.StatusCodes
    import akka.actor.ActorSystem
    import akka.stream.ActorMaterializer
    import com.typesafe.config.ConfigFactory
    import akka.event.Logging
    import akka.http.scaladsl.model._


    object ABC extends HttpApp with App {

          implicit val actorSystem = ActorSystem()
          implicit val matter = ActorMaterializer()                                                               
          val start = "hello"

        val Routing= {

            path(start) {
              redirect( Uri(start+ "/index.html"), StatusCodes.PermanentRedirect )
              } 
              ~
              pathPrefix(start) {         
                 content  

                }
            } 

val content = 
{ 
 get 
   {
    path("html") {
                 getFromResource("src/html") }
  }
}

}

Once you added the import as per @chunjef answer, also note that ~ is an infix operator, so it comes with all the "quirks" of it. To sort out your routes, you can avoid placing the ~ in a new line

    val Routing= {

        path(start) {
          redirect( Uri(start+ "/index.html"), StatusCodes.PermanentRedirect )
          } ~
          pathPrefix(start) {         
             content  

            }
        } 

or you can wrap the concatenated routes in brackets

   val Routing= {

        (path(start) {
          redirect( Uri(start+ "/index.html"), StatusCodes.PermanentRedirect )
          } 
          ~
          pathPrefix(start) {         
             content  

            })
        }