AccessControl.cs

// Specification before the actual check of the base-uri.
Spec<Uri> spec = 
    Spec.Of<Uri>()
        .Add(uri => uri.Scheme == Uri.UriSchemeHttps, "should be 'https' scheme");

// Demonstration purposes, generic type could be anything.
IObservable<T> obs = null;

// Access controlled function with validation, revocation, limited amount of evaluations and time-based availability.
Access<Uri, Uri> access =
    Access.OnlyUriFromBase(new Uri("https://localhost:9090/"))
          .Satisfy(spec)
          .Once()
          .DuringHours(9, 17)
          .RevokedWhen(obs);

// Somewhere else...
AccessResult<Uri> result = access.Eval(new Uri("http://localhost:9090/path"));
if (result.TryGetValue(out Uri output))
{
    // use the now correct 'output'
}