I gave the wildcard requirement a bit of thought, no inspiration at the
moment.
Maybe someone else can suggest a strategy.
Ambrose
On Sun, Nov 6, 2011 at 1:14 AM, Ambrose Bonnaire-Sergeant <
abonnaireserge...@gmail.com> wrote:
> Hey Michael,
>
> Here's a solution using core.logic.
>
> ;; We can define a "permission" relation with "defrel".
>
> (defrel permission roles ops state)
>
> ;; and a helper function to add each combination of permissions
>
> (defn add-permision [roles ops states]
> (for [r roles
> o ops
> s states]
> (fact permission r o s)))
>
> ;; Here is your first example
>
> (add-permision #{:admin :operator} #{:reject :accept} #{:applied})
>
> ;; Now lets ask what are the permissions for the :admin role
>
> logic-introduction.perm=> (run* [q]
> (fresh [ops states]
> (permission :admin ops states)
> (== q [ops states])))
> ([:reject :applied] [:accept :applied])
>
> ;; Ask what permissions either a :admin or :operator role has
>
> logic-introduction.perm=> (run* [q]
> (fresh [role ops states]
> (conde
> ((== role :admin))
> ((== role :operator)))
> (== q [ops states])
> (permission role ops states)))
> ([:reject :applied] [:accept :applied] [:reject :applied] [:accept
> :applied])
>
>
> Thanks,
> Ambrose
>
> On Sun, Nov 6, 2011 at 12:51 AM, Michael Jaaka <
> michael.ja...@googlemail.com> wrote:
>
>> Hi,
>>
>> I would like to use logic programing to describe permissions. The
>> definition is
>>
>> We have set of triples which looks like:
>> Set of roles; set of operations; set of states
>>
>> Triples are defined in scope of some entity with states, wildcard is
>> defined with _
>>
>> All I need is to answer on some operation invocation if given user
>> with his role is able to execute that operation for particular entity
>> which is in one of its states
>>
>> Example:
>> Roles: admin, operator, auditor
>> Entity: data form with states dirty, applied, rejected, executed
>> Operations on data form: reject, acept, list, enter
>> Triples of permissions:
>> admin, operator; reject, accept; applied
>> auditor, operator; list; _
>> operator; enter; dirty
>>
>> The additional question beside checking permission is:
>> What are operations avaiable for given role and given state of entity
>>
>>
>> Any thoughts? Maybe core.logic? It seems that I know its purpose but
>> don't know how to use it.
>> Thanks in advance.
>>
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>
>
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