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core-logic
tschady 2021-11-10T14:11:30.015900Z
I’m trying to compare elements inside an lvar which is a hashmap (in this case, having a unique value for the :a key). I’ve managed to do it with project but I’ve read this is to be avoided. Is there a better way to do this? Any advice on style? m will have over 100 entries eventually, with more complex comparison between adjacent vars.
(def m [{:a 1 :b "foo"}
{:a 1 :b "bar"}
{:a 3 :b "baz"}])
(let [vars (repeatedly 2 lvar)]
(run* [q]
(everyg #(membero % m) vars)
(project [vars] (distincto (mapv :a vars)))
(== q vars)))
paulocuneo 2021-11-10T14:38:21.016300Z
https://github.com/clojure/core.logic/blob/master/src/main/clojure/clojure/core/logic.clj#L2587 can be use to extract keys from a map, dunno the performance
(run* [q]
(fresh [ma a ma' a']
(membero ma m)
(membero ma' m)
(featurec ma {:a a})
(featurec ma' {:a a'})
(distincto [a a'])
(== [a a'] q)))
Ben Sless 2021-11-10T14:39:26.016600Z
Ninja'd by less than a minute featurec can bind keys and values in a map
tschady 2021-11-10T15:45:12.016900Z
I found featurec but hadn’t adapted my thinking to that a a' yet. thanks!