DI Demo - Better

Program.cs

var serviceCollection =
  new ServiceCollection()
    .AddSingleton<IWeatherServiceApi, UsWeatherServiceApi>()
    .AddSingleton<IWeatherServiceApi, CanadaWeatherServiceApi>()
    .AddSingleton<IWeatherServiceParser, UsWeatherServiceParser>()
    .AddSingleton<IWeatherServiceParser, CanadaWeatherServiceParser>()
    .AddSingleton<Func<string, IWeatherServiceApi>>(WeatherServiceApiFactory)
    .AddSingleton<Func<string, IWeatherServiceParser>>(WeatherServiceParserFactory)
    .AddSingleton<TextWriter>(Console.Out)
    .AddSingleton<TextReader>(Console.In)
    .AddSingleton<IWeatherService, WeatherService>()
    .AddSingleton<IDIDemoService, DIDemoService>();
          
...

private static Func<IServiceProvider, Func<string, IWeatherServiceApi>> WeatherServiceApiFactory =>
  service =>
  {
    return
      postalCode =>
      {
        if (IsUsZipCode(postalCode))
        {
          return service.GetServices<IWeatherServiceApi>().First(s => s is UsWeatherServiceApi);
        }
        if (IsCanadianPostalCode(postalCode))
        {
          return service.GetServices<IWeatherServiceApi>().First(s => s is CanadaWeatherServiceApi);
        }

        throw new ArgumentException("Could not determine location");
      };
  };

private static Func<IServiceProvider, Func<string, IWeatherServiceParser>> WeatherServiceParserFactory =>
  service =>
  {
    return
      postalCode =>
      {
        if (IsUsZipCode(postalCode))
        {
          return service.GetServices<IWeatherServiceParser>().First(s => s is UsWeatherServiceParser);
        }
        if (IsCanadianPostalCode(postalCode))
        {
          return service.GetServices<IWeatherServiceParser>().First(s => s is CanadaWeatherServiceParser);
        }

        throw new ArgumentException("Could not determine location");
      };
  };