gistfile1.cs

var maybeNick = NicknamesToEmail
	.Where(x => x.Nickname == fullNameOrEmail)
	.Select(x => x.Email)
	.ToMaybe();	
			
var maybeName = FullNamesToEmail
	.Where(x => x.FullName == fullNameOrEmail)
	.Select(x => x.Email)
	.ToMaybe();	

var maybePrefs = from name in new[] { maybeNick, maybeName}
		from prefs in EmailToPreferences
		where !name.IsNone
		where prefs.Email == name.Some
				select prefs.EmailPreferences;

return maybePrefs.ToMaybe();

	internal static class EnumerableExtensions
	{
		public static Maybe<T> ToMaybe<T>(this IEnumerable<T> instance)
		{
			if (!instance.Any())
				return Maybe<T>.None;

			return Maybe.From(instance.First());
		}
	}