sS tok_formatDollarVars(S pat, MapSO vars) {
  if (empty(vars)) ret pat;
  MapSO vars2 = mapKeys addDollarPrefix(vars);
  ifdef tok_formatDollarVars_debug
    printVars tok_formatDollarVars(+pat, +vars, +vars2);
  endifdef
  LS tok = javaTok(pat);
  for (int i = 1; i < l(tok); i += 2) {
    S var = tok.get(i);
    if (!isIdentifier(var)) continue;
    S value = strOrNull(vars2.get(var));
    if (value != null) tok.set(i, value);
  }
  S output = join(tok);
  ifdef tok_formatDollarVars_debug
    printVars tok_formatDollarVars(+output);
  endifdef
  ret output;
}

sS tok_formatDollarVars(S pat, O... _) {
  ret tok_formatDollarVars(pat, paramsToMap(_));
}

Began life as a copy of #1010857