Blog comment from uvwu on http://lostechies.com/sharoncichelli/2014/01/13/maybe-that-shouldnt-be-settable/. Code transcribed by me, so blame me for any typos.

ResultCompanion.cs

public static class Result
{
    private const int UNKNOWN_STATUS_CODE = -1;
    private const string UNKNOWN_STATUS_PHRASE = @"WAT?";

    public static Result<t> Success(T result = default(T))
    {
        return Result<t>.Success(new[] { result });
    }

    public static Result<t> Error(int statusCode = UNKNOWN_STATUS_CODE,
                                  string reasonPhrase = UNKNOWN_STATUS_PHRASE)
    {
        return new Result<t>.Error(statusCode, reasonPhrase);
    }
}

SuccessTypeInterface.cs

public static Result<t> ToResult<t>(this HttpResponseMessage response)
{
    return response.IsSuccessStatusCode
        ? Result.Success(Deserialize(response))
        : Result.Error<coolthing>(response.StatusCode, response.ReasonPhrase);
}