Hi,
I'm trying to use featurec to describe some relationships within a nested
map. When I try to use it to find some keys in the map it returns nothing.
Here is an example:
;; Here is a map of some foods
> (def foods {:apple {:color "Red"}
> :carrot {:color "Orange"}
> :tomato {:color "Red"}
> :celery {:color "Green"}})
> ;; What is the :color of :apple?
> ;; This works -- it returns ("Red")
> (run* [q]
> (featurec foods {:apple {:color q}}))
> ;; Show me every food that has the :color "Red"
;; I expect to get back (:apple :tomato)
;; This doesn't work -- it returns ()
> (run* [q]
> (featurec foods {q {:color "Red"}}))
> ;; Give me the name of a key for :apple that has the value "Red"
;; This should return (:color)
;; This doesn't work -- it returns ()
> (run* [q]
> (featurec foods {:apple {q "Red"}}))
I realize there is a good chance I am trying to ask featurec to do
something it isn't designed for. Is this true? If so, what is a better way?
One solution I have come up with is to massage the map into a vector like
this:
;; The foods as maps within a vector and the names as values instead of keys
> (def vector-of-foods [{:name "Apple" :color "Red"}
> {:name "Carrot" :color "Orange"}
> {:name "Tomato" :color "Red"}
> {:name "Celery" :color "Green"}])
> ;; What foods are :color "Red" ?
> ;; This works -- it returns ("Apple" "Tomato")
> (run* [q]
> (fresh [f]
> (membero f vector-of-foods)
> (featurec f {:color "Red"})
> (featurec f {:name q})))
I would do this if the data I was dealing with was just the colors of food,
but what I am really trying to do is use core.logic to create programs that
understand relationships in AWS
CloudFormation<http://aws.amazon.com/cloudformation/> templates.
A CFN template is a JSON file that is a bunch of nested maps that describe
cloud computing infrastructure. I feel there are risks to massaging the
templates and featurec feels right. What am I missing? Any guidance is
appreciated.
Thanks,
Dave
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