result.cs

    public class Result<T> : Result
    {
        public T Value { get; }
        public Result(T result)
        {
            Success = true;
            Value = result;
        }

        public Result()
        {

        }
        
        public static implicit operator Result<T>(string error)
        {
            return new Result<T> { Error = error, Success = false };
        }
        
        public Result<TRes> Map<TRes>(Func<T, TRes> cb)
        {
            if (Success)
                return Result.Create(cb(Value));
            return Error;
        }

        public bool TryGetValue(out T value)
        {
            value = Value;
            return Success;
        }

        public bool Get(out T value, out string error)
        {
            value = Value;
            error = Error;
            return Success;
        }
    }

    public class Result
    {
        public static Result<T> Create<T>(T result) => new Result<T>(result);
        public bool Success { get; protected set; }
        public string Error { get; protected set; }

        public Result()
        {
            Success = true;
        }

        public static Result Succeeded { get; } = new Result();
        
        
        public static implicit operator Result(string error)
        {
            return new Result { Error = error, Success = false };
        }

        public Result<TRes> Map<TRes>(Func<TRes> cb)
        {
            if (Success)
                return Result.Create(cb());
            return Error;
        }

        public Result<TRes> Map<TRes>(Func<Result<TRes>> cb)
        {
            if (Success)
                return cb();
            return Error;
        }
    }