static <A, B> F1<A, B> codeToFunctionOnArbitraryType(S code, S type, Class<A> javaType, S varName) {
  code = trim(code);
  Class c;
  S methodName;
  if (isIdentifier(code)) { // name of standard function
    c = loadFunctions_cached_withInit(code);
    methodName = code;
  } else if (jcontains(code, "calc(")) { // code defines its own calc function
    c = veryQuickJava(code);
    methodName = 'calc;
  } else { // code is an expression or block working on variable s
    S main = "sO calc(final " + type + " " + varName + ") {\n" + tok_addReturn(code) + "\n}";
    c = veryQuickJava(main);
    methodName = 'calc;
  }
  
  final Method m = findMethod_precise_onTypes(c, methodName, javaType);
  if (m == null) fail("Not a method on " + c + ": " + code + "(" + javaType + ")");
  ret (F1) func(O o) -> O { invokeMethod(m, null, o) };
}