Corlib .NStar (Pre-Pre-Alpha) 0.05. Теперь отдельно от нелюбимого многими языка!

return AllEnumerable(new List<TSource>(source), function);

    internal static bool TryGetCountEasilyEnumerable<TSource>(IEnumerable<TSource> source, out int count)
    {
        if (source is ICollection<TSource> col)
        {
            count = col.Count;
            return true;
        }
        else if (source is IReadOnlyCollection<TSource> col2)
        {
            count = col2.Count;
            return true;
        }
        else if (source is string s)
        {
            count = s.Length;
            return true;
        }
        else
        {
            count = -1;
            return false;
        }
    }

    internal const int HashPrime = 101;
    internal const int MaxPrimeArrayLength = 0x7FEFFFFD;
    internal static readonly int[] primes = {
            3, 7, 11, 17, 23, 29, 37, 47, 59, 71, 89, 107, 131, 163, 197, 239, 293, 353, 431, 521, 631, 761, 919,
            1103, 1327, 1597, 1931, 2333, 2801, 3371, 4049, 4861, 5839, 7013, 8419, 10103, 12143, 14591,
            17519, 21023, 25229, 30293, 36353, 43627, 52361, 62851, 75431, 90523, 108631, 130363, 156437,
            187751, 225307, 270371, 324449, 389357, 467237, 560689, 672827, 807403, 968897, 1162687, 1395263,
            1674319, 2009191, 2411033, 2893249, 3471899, 4166287, 4999559, 5999471, 7199369};

global using System;
global using System.IO;
global using System.Net.Http;
global using System.Threading;
global using System.Threading.Tasks;
global using E = System.Linq.Enumerable;
global using G = System.Collections.Generic;
using Corlib.NStar;
using System.Diagnostics;
 
// See https://aka.ms/new-console-template for more information
Random random = new(1234567890);
Console.WriteLine("Hello World!");
var list = OptimizedLinq.Fill(x => random.Next(0, 65536), 10000000);
Stopwatch sw = Stopwatch.StartNew();
var a = E.ToDictionary(E.Where(E.GroupBy(E.Zip(E.Skip(list, 1), E.Skip(list, 2), (x, y) => ((ulong)(uint)x << 32) + (uint)y), x => x), x => E.Count(x) >= 2), x => x.Key, col => E.ToList(E.OrderBy(col, x => (uint)x)));
sw.Stop();
Console.WriteLine(sw.ElapsedMilliseconds);
sw.Restart();
var b = list.AsSpan(1).Combine(list.AsSpan(2), (x, y) => ((ulong)(uint)x << 32) + (uint)y).Group(new EComparer<ulong>((x, y) => x == y, x => (int)(x >> 32) ^ (int)x)).FilterInPlace(x => x.Length >= 2).ToDictionary(x => x.Key, col => col.Sort());
sw.Stop();
Console.WriteLine(sw.ElapsedMilliseconds);
Console.WriteLine(OptimizedLinq.Equals(a, b, (x, y) => x.Key == y.Key && OptimizedLinq.Equals(x.Value, y.Value, (x, y) => x == y)));

var s = new string('a', 1000000000);
Stopwatch sw = Stopwatch.StartNew();
var a = E.Count(s);
sw.Stop();
Console.WriteLine(sw.ElapsedMilliseconds);
sw.Restart();
var b = s.Count();
sw.Stop();
Console.WriteLine(sw.ElapsedMilliseconds);

Random random = new(1234567890);
Console.WriteLine("Hello World!");
var list = OptimizedLinq.Fill(x => random.Next(0, 65536), 100000000);
Stopwatch sw = Stopwatch.StartNew();
var a = new G.HashSet<int>(list);
sw.Stop();
Console.WriteLine(sw.ElapsedMilliseconds);
sw.Restart();
var b = new ParallelHashSet<int>(list);
sw.Stop();
Console.WriteLine(sw.ElapsedMilliseconds);
Console.WriteLine(b.SetEquals(a));