Memoization

Memoization.cs

   public static class Memoization
    {
        public static Func<TA, TR> Memoize<TA, TR>(Func<TA, TR> f)
        {
            var map = new Dictionary<TA, TR>();

            return a =>
            {
                lock (map)
                {
                    TR value;

                    if (map.TryGetValue(a, out value))
                    {
                        return value;
                    }

                    value = f(a);
                    map.Add(a, value);

                    return value;

                }
            };
        }
    }