src/Pure/System/scala.ML

 
 (* invoke function *)
 
 fun promise_function name arg =
   let
-    val _ = if Resources.is_pide () then () else raise Fail "PIDE session required";
     val id = new_id ();
     fun abort () = Output.protocol_message (Markup.cancel_scala id) [];
     val promise = Future.promise_name "invoke_scala" abort : string future;
     val _ = Synchronized.change promises (Symtab.update (id, promise));
     val _ = Output.protocol_message (Markup.invoke_scala name id) [XML.Text arg];