Exemple of features of C#8 (It's not mine)

CSharp8.cs

interface IProcessor<T,U> where T: unmanaged, IResult
{
    T ProcessSingle(int x);

    async IAsyncEnumerable<T> ProcessMany(int[] xs, int batch)
    {
        static T[] ProccessBatch(Func<int,T> func, Span<int> list, in Range range)
        {
            (_, int length) = range.GetOffsetAndLenght(list.length);
            using var batcher = new Batcher<T>(stackalloc T[length]);
            return batcher.Proccess(func, list[range]);
        }

        for(int i = 0; i < xs.Length; i += batch)
        {
            foreach (var t in ProccessBatch(ProccessSingle, xs, i..(i+batch)))
            {
                yield return t switch
                {
                    { IsSucceeded:false} => (T)IResult.Failed,
                    { IsSucceeded:true, Description:null} => (T)IResult.Failed,
                    _ => await Task.FromResult(t)
                }
            }
        }
    }
}