using System;

​

namespace ResultPatern

{

    public sealed record Error(string Code, string Message = null);

    public class Result<TValue, TError>

    {

        public readonly TValue Value;

        public readonly TError Error;

        private bool _isSuccess;

        private Result(TValue value)

        {

            _isSuccess = true;

            Value = value;

            Error = default;

        }

​

        private Result(TError error)

        {

            _isSuccess = false;

            Value = default;

            Error = error;

        }

​

        //happy path

        public static implicit operator Result<TValue, TError>(TValue value) => new Result<TValue, TError>(value);

        //error path

        public static implicit operator Result<TValue, TError>(TError error) => new Result<TValue, TError>(error);

        public Result<TValue, TError> Match(Func<TValue, Result<TValue, TError>> success, Func<TError, Result<TValue, TError>> failure)

        {

            return _isSuccess ? success(Value!) : failure(Error!);

        }

    }

​

    public static class DivedErrors

    {

        public static readonly Error DivisionByZero = new("Dived.DivisionByZero", "Division by zero is not allowed.");

        public static readonly Error DivisionByOne = new("Dived.DivisionByOne", "Division by 1 always results in the dividend.");

    }

​

    internal class Program

    {

        public static Result<int, Error> Divide(int numerator, int denominator)

        {

            if (denominator == 0)

            {

                return DivedErrors.DivisionByZero;

            }

​

            if (denominator == 1)

            {

                return DivedErrors.DivisionByOne;

            }

​

            int result = numerator / denominator;

            return result;

        }

​

        static void Main(string[] args)

        {

            Result<int, Error> divisionResult = Divide(4, 4);

            Result<int, Error> rslt = divisionResult.Match(result => result, err => err);

            if (rslt.Error != null)

            {

                Console.WriteLine(rslt.Error.Message);

            }

            else

            {

                Console.WriteLine(rslt.Value);

            }

​

            Console.ReadLine();

        }

    }

}