(featurec x fs)
Ensure that a map contains at least the key-value pairs in the map fs. fs must be partially instantiated - that is, it may contain values which are logic variables to support feature extraction.
user> (run 1 [q] (featurec q {1 2}) (== q {2 4}))
() ;; {2 4} does not cointain k-v 1 2
user> (run 1 [q] (featurec q {1 2}) (== q {1 2 2 4}))
({1 2, 2 4}) ;; {1 2 2 4} does contain k-v 1 2
;; http://michaelrbernste.in/2013/05/12/featurec-and-maps.html
;; http://stackoverflow.com/questions/15821718/how-do-i-de-structure-a-map-in-core-logic
(is (= (run* [q]
(featurec q {:foo 1})
(== q {:foo 1 :bar 2}))
'({:foo 1 :bar 2})))