!7

static O host;
static SimpleLiveValue<S> lv = new(S);
static S last;
static ReliableSingleThread rst = new(f parse);

static JComponent visualize() {
  ret jLiveValueTextArea(lv); 
}

svoid update {
  S s = cast callOpt(creator(), 'getInterestingString);
  if (neq(s, last)) {
    last = s;
    rst.trigger();
  }
}

svoid parse {
  S text;
  lv.set("Parsing...");
  try {
    javaParseCompilationUnit(last);
    text = "Text parses as Java compilation unit";
  } catch e {
    text = firstLine(getInnerMessage(e));
  }
  lv.set(text);
}