Printing Hello, World! with nested enumerables.

Tailor.cs

namespace Tailor;

using System.Collections;
using System.Collections.Generic;

public static class EnumerableExt 
{
    public static IEnumerable<T> Tail<T>(this IEnumerable<T> source) 
    {
        return new TailEnumerable<T>(source);
    }
}

public class TailEnumerable<T> : IEnumerable<T>
{
    private readonly IEnumerable<T> _enumerable;

    public TailEnumerable(IEnumerable<T> enumerable) 
    {
        _enumerable = enumerable;
    }

    public IEnumerator<T> GetEnumerator()
    {
        return new TailEnumerator<T>(_enumerable.GetEnumerator());
    }

    IEnumerator IEnumerable.GetEnumerator()
    {
        return GetEnumerator();
    }
}

public class TailEnumerator<T> : IEnumerator<T>
{
    private readonly IEnumerator<T> _enumerator;

    public TailEnumerator(IEnumerator<T> enumerator) 
    {
        _enumerator = enumerator;
        if (!MoveNext()) {
            throw new Exception("No tail!");
        }
    }

    public bool MoveNext()
    {
        Console.Write("->");
        return _enumerator.MoveNext();
    }

    public T Current
    {
        get { return _enumerator.Current; }
    }

    object? IEnumerator.Current
    {
        get { return Current; }
    }

    public void Dispose() { }

    public void Reset()
    {
        _enumerator.Reset();
    }
}

class Program
{
    static void Main(string[] args)
    {
        IEnumerable<char> s = "Hello, World!";
        while (s.Any()) {
            var ch = s.First();
            Console.WriteLine(ch);
            s = s.Tail();
        }

        Console.ReadKey();
    }
}