!7

sclass ThoughtSpaces {
  new L<ThoughtSpace1> spaces;
  new L<ThoughtSpace1> activeSpaces;
  
  void add(ThoughtSpace1 ts) {
    spaces.add(ts);
    activeSpaces.add(ts);
  }
  
  bool think() {
    ThoughtSpace1 ts = first(activeSpaces);
    if (ts == null) false;
    activeSpaces.remove(ts);
    ts.think(true);
    true;
  }
}

p-exp {
  new ThoughtSpace1 ts;
  ts.setInput("let's have a cup of Joe");
  ts.add(Definition("let's have", "a grouping prefix"));
  ts.addStepper(ts1_applyGroupingPrefix());
  ts.lookingFor.add(ProposeRewrite);
  new ThoughtSpaces spaces;
  spaces.add(ts);
  while (spaces.think());
}

Began life as a copy of #1017048