Simple demonstration that mutating an array in C# doesn't change its hash function, in contrast with Ruby.

HashOnMutatedArray.cs

using System;
using System.Collections.Generic; 

namespace array_compare
{
    class Program
    {
        static void DoesItChange() 
        {
            Dictionary<int[], string> hash = new Dictionary<int[], string>(); 
            int[] mutableArray = new int[] { 1,2 }; 
            hash[mutableArray] = "foo"; 
            Console.WriteLine(hash[mutableArray]); // prints "foo"
            mutableArray[1] = 3; 
            Console.WriteLine(hash[mutableArray]); // prints "foo"      
        }
        static void Main(string[] args)
        {
            DoesItChange();
        }
    }
}