Fixed query fn results unification (closes #490)

Author: tonsky

CHANGELOG.md

@@ -1,3 +1,7 @@
+# WIP
+
+- Fixed query fn results unification #490
+
 # 1.7.5 - May 4, 2025
 
 - Enable direct-linking on JVM #487 via @raspasov

src/datascript/query.cljc

@@ -167,7 +167,8 @@
           (sum-rel b))))))
 
 (defn prod-rel
-  ([] (Relation. {} [(da/make-array 0)]))
+  ([]
+   (Relation. {} [(da/make-array 0)]))
   ([rel1 rel2]
    (let [attrs1 (keys (:attrs rel1))
          attrs2 (keys (:attrs rel2))
@@ -544,12 +545,18 @@
                          rels     (for [tuple (:tuples production)
                                         :let  [val (tuple-fn tuple)]
                                         :when (not (nil? val))]
-                                    (prod-rel (Relation. (:attrs production) [tuple])
-                                      (in->rel binding val)))]
+                                    (reduce prod-rel
+                                      (collapse-rels
+                                         [(Relation. (:attrs production) [tuple])]
+                                         (in->rel binding val))))]
                      (if (empty? rels)
-                       (prod-rel production (empty-rel binding))
+                       (prod-rel
+                         production
+                         (empty-rel binding))
                        (reduce sum-rel rels)))
-                   (prod-rel (assoc production :tuples []) (empty-rel binding)))]
+                   (prod-rel
+                     (assoc production :tuples [])
+                     (empty-rel binding)))]
     (update context :rels collapse-rels new-rel)))
 
 ;;; RULES

test/datascript/test/query_fns.cljc

@@ -79,7 +79,8 @@
       (is (= (d/q '[:find  ?a1
                     :where [_ :age ?a1]
                     [(>= ?a1 22)]] db)
-            #{[22] [37]}))      
+            #{[22] [37]}))
+
       (testing "compare values of different types"
         (is (= (d/q '[:find  ?e
                       :where [?e]
@@ -137,20 +138,23 @@
 
     (testing "Two conflicting function values for one binding."
       (is (= (d/q '[:find  ?n
-                    :where [(identity 1) ?n]
+                    :where
+                    [(identity 1) ?n]
                     [(identity 2) ?n]])
             #{})))
 
     (testing "Destructured conflicting function values for two bindings."
       (is (= (d/q '[:find  ?n ?x
-                    :where [(identity [3 4]) [?n ?x]]
+                    :where
+                    [(identity [3 4]) [?n ?x]]
                     [(identity [1 2]) [?n ?x]]])
             #{})))
 
     (testing "Rule bindings interacting with function binding. (fn, rule)"
       (is (= (d/q '[:find  ?n
                     :in $ %
-                    :where [(identity 2) ?n]
+                    :where
+                    [(identity 2) ?n]
                     (my-vals ?n)]
                db
                '[[(my-vals ?x)
@@ -229,6 +233,17 @@
                [])
             #{})))))
 
+;; issue-490
+(deftest test-fn-call-results-unification
+  (is (= #{[[:a :a] :a]}
+        (d/q '[:find ?p ?x
+               :where
+               [_ :pair ?p]
+               [(clojure.core/first  ?p) ?x]
+               [(clojure.core/second ?p) ?x]]
+          [[1 :pair [:a :a]]
+           [2 :pair [:b :c]]]))))
+
 (deftest test-predicates
   (let [entities [{:db/id 1 :name "Ivan" :age 10}
                   {:db/id 2 :name "Ivan" :age 20}