C# memoize higher order functions by using tuples

memoize.cs

using System;
using System.Collections.Concurrent;

namespace ns
{
  //even though this looks like it only takes functions with one input
  // by using C# tuple types, one can have any number of inputs (or outputs)
  // see example below
  public class Memoized<T, TResult>
  {
    public Memoized(Func<T, TResult> func) => _func = func;

    private readonly Func<T, TResult> _func;
    private readonly ConcurrentDictionary<T,TResult> _cache = new ConcurrentDictionary<T, TResult>();
    public TResult Get(T input) => _cache.GetOrAdd(input, _func);
  }

  public static class MemoizedExtensions
  {
    public static Func<T, TResult> Memoize<T, TResult>(this Func<T, TResult> func) => new Memoized<T, TResult>(func).Get;
  }
  
  
  class Program
  {
    static void Main()
    {
      var fun = new Func<(double x, double y , double z), (double x, double y, double z)>(inverse).Memoize();

      Console.WriteLine("fun: " + fun((1.1, 2.1, 3.1))); // will WriteLine in 'inverse' function the first time
      Console.WriteLine("fun: " + fun((1.1, 2.1, 3.1))); // will directly return result after called once
      Console.WriteLine("fun: " + fun((1.1, 2.1, 3.1)));
    }

    static (double x, double y, double z) inverse((double x, double y, double z) vec)
    {
      var (x, y, z) = vec;
      Console.WriteLine(string.Format("{0} called ({1}, {2}, {3})", nameof(inverse), x, y, z));
      return (-x, -y, -z);
    }
  }

}