Proper (reduced) handling in transducers

src-clj/acha/server.clj

@@ -63,11 +63,12 @@
 (defn- entity->flat [rf]
   (completing
     (fn [result entity]
-      (reduce-kv (fn [result attr val]
-                   (if (= attr :db/id)
-                     result
-                     (rf result [(:db/id entity) attr val])))
-                 result entity))))
+      (util/-reduce-kv
+        (fn [result attr val]
+          (if (= attr :db/id)
+            result
+            (rf result [(:db/id entity) attr val])))
+        result entity))))
 
 (defn full-dump []
   (let [ent->datoms (comp entity->flat

src-clj/acha/util.clj

@@ -107,3 +107,23 @@
 (defn max-by [f [x & xs]]
   (reduce #(if (pos? (compare (f %1) (f %2))) %1 %2) x xs))
 
+(defn -reduce
+  "Variant of reduce that does not unwrap (reduced)"
+  [f init coll]
+  (reduce #(let [result (f %1 %2)]
+                (cond-> result
+                  ;; wrap twice because reduce will unwrap one reduced
+                  ;; but we want to pass that info down the line
+                  (reduced? result) reduced))
+           init coll))
+
+(defn -reduce-kv
+  "Variant of reduce-kv that does not unwrap (reduced)"
+  [f init coll]
+  (reduce-kv #(let [result (f %1 %2 %3)]
+                (cond-> result
+                  ;; wrap twice because reduce-kv will unwrap one reduced
+                  ;; but we want to pass that info down the line
+                  (reduced? result) reduced))
+             init coll))
+