clash-of-styles-operations-matrix-via-oop

OperationsMatrixViaOop.cs

using System;

namespace OOPvsFP
{
    class Program
    {
        static void Main(string[] args)
        {
            var expression = new Addition(
                new MyInt(3), 
                new Addition(new MyInt(4), new MyInt(5)));
            
            var asString = expression.Stringify();
            var result = expression.Eval();
            
            Console.WriteLine($"{asString} = {result}"); // 3 + 4 + 5 = 12
        }
    }

    public interface IExpression
    {
        int Eval();
        string Stringify();
    }

    public class MyInt : IExpression
    {
        private int Val { get; } 
        
        public MyInt(int val)
        {
            Val = val;
        }

        public int Eval() => Val;
        public string Stringify() => Val.ToString();
    }
    
    public class Addition : IExpression
    {
        private readonly IExpression _operand1;
        private readonly IExpression _operand2;

        public Addition(IExpression operand1, IExpression operand2)
        {
            _operand1 = operand1;
            _operand2 = operand2;
        }

        public int Eval() => _operand1.Eval() + _operand2.Eval();

        public string Stringify() => $"{_operand1.Stringify()} + {_operand2.Stringify()}";
    }
}