Memoization in C#: One Input

memoization_one_input.cs

public static Func<TSource, TReturn> Memoize<TSource, TReturn>(Func<TSource, TReturn> func)
{
    var cache = new Dictionary<TSource, TReturn>();
    return s =>
    {
        if (!cache.ContainsKey(s))
        {
            cache[s] = func(s);
        }
        return cache[s];
    };
}