SequenceEqualityComparer.cs

public sealed class SequenceEqualityComparer<T> : IEqualityComparer<IEnumerable<T>>
{
    public readonly IEqualityComparer<T> Comparer;

    public SequenceEqualityComparer(IEqualityComparer<T>? comparer = null)
    {
        Comparer = comparer ?? EqualityComparer<T>.Default;
    }

    public static readonly SequenceEqualityComparer<T> Instance = new();

    public bool Equals(IEnumerable<T>? x, IEnumerable<T>? y)
    {
        var xIsNull = x is null;
        var yIsNull = y is null;

        if (xIsNull && yIsNull)
            return true;
        
        if (xIsNull || yIsNull)
            return false;

        using var xEnumerator = x.GetEnumerator();
        using var yEnumerator = y.GetEnumerator();
        while (true)
        {
            var xNext = xEnumerator.MoveNext();
            var yNext = yEnumerator.MoveNext();

            if(!xNext && !yNext)
                break;

            if (xNext != yNext)
                return false;

            if (!Comparer.Equals(xEnumerator.Current, yEnumerator.Current))
                return false;
        }

        return true;
    }

    public int GetHashCode(IEnumerable<T> sequence)
    {
        var hash = new HashCode();

        foreach (var element in sequence)
            hash.Add(element);

        return hash.ToHashCode();
    }
}