static S replaceVars_withDollarQ(S s, SS map) {
  ret empty(map) ? s : join(replaceVars_withDollarQ(javaTok(s), map));
}
  
static LS replaceVars_withDollarQ(LS tok, SS map) {
  if (empty(map)) ret tok;
  tok = cloneList(tok);
  for (int i = 1; i < l(tok); i +=2) {
    S t = tok.get(i);
    S value = map.get(t);
    if (value != null)
      tok.set(i, value);
    else if (t.startsWith("$_q_")) {
      value = map.get("$" + substring(t, 4));
      if (value != null) tok.set(i, quote(value));
    }
  }
  ret tok;
}

Began life as a copy of #1004293