static Map<S, T3<S>> ai_parseTriple_cache = synchronizedMRUCache(1000);

static T3<S> ai_parseTriple(S s) {
  T3<S> t = ai_parseTriple_cache.get(s);
  if (t != null) ret t;
  L<S> l = map tok_unCurlyBracket(splitAtSimpleArrow(tok_combineCurlyBrackets_keep(javaTok(s))));
  if (l(l) == 2) l.add(".");
  t = listToTriple(l);
  ai_parseTriple_cache.put(s, t);
  ret t;
}