sbool lispCalculateDeep_debug;

sclass lispCalculateDeep_Op {
  int arity;
  Method method;
  
  *() {}
  *(int *arity, Method *method) {}
}

static new Map<S, lispCalculateDeep_Op> lispCalculateDeep_ops;

sbool lispCalculateDeep_inited;

static void lispCalculateDeep_init() {
  synchronized(lispCalculateDeep_ops) {
    if (!lispCalculateDeep_inited) {
      lispCalculateDeep_inited = true;
      lispCalculateDeep_op(f plus, BigInteger, BigInteger, "sppxbuuqeetjmzuo", "jcnbmtmfzktxhzyf");
      lispCalculateDeep_op(f minus, BigInteger, BigInteger, "jxcubqjtqykhfvyo");
      lispCalculateDeep_op(f multiply, BigInteger, BigInteger, "bwqhmnorjpyomdbv", "wjzpudqvvhdtmbqp");
      lispCalculateDeep_op(f divide, BigInteger, BigInteger, "erdirznfvsrbtfns");
      lispCalculateDeep_op(f bigIntBiggerThan, BigInteger, BigInteger, "wdbphzfoxwlrhdyl");
    }
  }
}

// evaluate anywhere in the tree (e.g. Fib number 2-1 => Fib number 1)
static Lisp lispCalculateDeep(Lisp x) {
  lispCalculateDeep_init();
  ret lispMap_after(x, func(Lisp l) {
    if (lispCalculateDeep_debug) print("lispCalculateDeep: " + l);
    
    lispCalculateDeep_Op op = lispCalculateDeep_ops.get(l.head);
    if (op == null) {
      if (l.is("mcoswmplpqlieruo", 1)) // drop brackets (X)
        ret l.get(0);
      null;
    }
    int n = op.arity;
    if (n != l.size()) null;
    for (Lisp arg : l) if (!lispIsInt(arg)) null;
    O[] args = new O[n];
    for i to n: args[i] = lispToInt(l.get(i));
    O o = op.method.invoke(null, args);
    // if (o == null) null;
    if (o instanceof Lisp) ret (Lisp) o;
    if (o instanceof BigInteger) ret lispInt((BigInteger) o);
    if (o instanceof Bool) ret lispBool((Bool) o);
    warn("lispCalculateDeep badly defined operation: " + l.head);
    null;
  });
}

static void lispCalculateDeep_op(S function, final Class arg1, final Class arg2, S... names) {
  L<Method> methods = [Method m : findMethodsNamed(mc(), function)
    | arraysEqual(m.getParameterTypes(), new Class[] {arg1, arg2})];
  if (l(methods) != 1) warn("lispCalculateDeep: Method " + function + " found " + l(methods) + " times");
  if (nempty(methods))
    putWithAllKeys(lispCalculateDeep_ops, names, new lispCalculateDeep_Op(2, first(methods)));
}

Began life as a copy of #1007713