According to QVT - operational specification, a helper with side effect can be declared as:

helper computeCandidates(inout studentList:Sequence(String)) : Sequence(String) {
var newStudent:String := "a new Student";
studentList += newStudent;
return studentList;
}

But in eclipse QVTO transformation project, This crates an error stating:

"Can't assign a value to 'inout' parameter 'studentList'"

Any ideas on how to fix this?

main() {
  var list = Sequence{};
  var list2 = computeCandidates(list);
  assert (list2 = Sequence{"a new Student"});
  ...