Btw. Is there any fine tutorial for core.logic? By fine I mean
something like learn haskell for great good.
On 5 Lis, 20:26, Michael Jaaka <michael.ja...@googlemail.com> wrote:
> Now is ok, easy to grasp. How the lein dep declaration and clj import
> looks?
> Thank you both.
>
> On 5 Lis, 20:11, David Nolen <dnolen.li...@gmail.com> wrote:
>
>
>
>
>
>
>
> > I would probably write the code like this:
>
> > (defrel permission role op state)
>
> > (defn add-permision [roles ops states]
> > (doseq [r roles o ops s states]
> > (fact permission r o s)))
>
> > (add-permision #{:admin :operator} #{:reject :accept} #{:applied})
>
> > (defn permissiono [role op state]
> > (run* [q]
> > (permission role op state)
> > (== q {:role role :op op :state state})))
>
> > (permissiono :admin (lvar) (lvar))
>
> > ;; ({:role :admin, :op :reject, :state :applied}
> > ;; {:role :admin, :op :accept, :state :applied})
>
> > We can use (lvar) for wildcards. If nothing can satisfy the query you'll
> > get back an empty sequences.
>
> > What in particular do you find unsatisfactory about this interface?
>
> > On Sat, Nov 5, 2011 at 2:46 PM, Michael Jaaka
> > <michael.ja...@googlemail.com>wrote:
>
> > > Thanks, it gave me insight into that framework.
> > > Unfortunately it doesn't look friendly in usage.
> > > Looks like there is a place for a clojure lib or wrapper around
> > > core.logic.
> > > It would be nice if it could answer to questions also in terms of
> > > truth.
>
> > > On 5 Lis, 18:24, Ambrose Bonnaire-Sergeant
> > > <abonnaireserge...@gmail.com> wrote:
> > > > 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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