Conditionally return object if related to subject via pattern

[bionicles]

We often describe authorization rules in terms of graph traversals. Role-based access control and access control lists are not really suited for it

Example: Doctors who work on the care team for a patient or group of patients can view patient data including lab results, images, procedures, conditions etc

To describe all of these possible traversals specifically is impossible due to combinatorial explosion

Is it possible to express this sort of traversal with optional steps and branching steps:

Ex. ["Provider", "CareTeam", {"Group", None}, "Patient", {"Observation", "Condition", "Procedure", ...} ]

Could yield a vast array of possible traversals in one line of python itertools

Is it possible to conditionally execute dataflows if the flow-path from the requesting user to the requested data matches some generator of flow-paths?

That could make security rules a lot more expressive and a lot easier to maintain. Also could make this into a nice functional query language for databases.

What do you think?