AnyExpression using array variables can't be evaluated with error 0 about expression HOT 1 CLOSED

func expression(_ X: [CGFloat], _ expression: String) {
    let x = X.map { Double($0) }
    let eval = AnyExpression(
        Expression.parse(expression.lowercased()),
        impureSymbols: { _ in nil },
        pureSymbols: { symbol in
            switch symbol {
            case .variable("x"):
                return { _ in x }
            case let symbol:
                guard let scalarFn = Expression.mathSymbols[symbol] else {
                    return nil
                }
                return { args in
                    guard args.count == 2, let arrays = args as? [[Double]] else {
                        guard let args = args as? [Double] else {
                            throw Expression.Error.typeMismatch(symbol, args)
                        }
                        return try scalarFn(args)
                    }
                    return try zip(arrays[0], arrays[1]).map { try scalarFn([$0, $1]) }
                }
            }
        }
    )
    do {
        let result: [CGFloat] = try eval.evaluate()
        print(result)
    } catch {
        print(error)
    }
}