From ba268a1eae38e0eb474675c2c5b626a45514babb Mon Sep 17 00:00:00 2001
From: davidnolen <david.nolen@gmail.com>
Date: Sun, 19 Oct 2025 10:56:01 -0400
Subject: [PATCH 1/4] ObjMap, return original map if new kv is identical

---
 src/main/cljs/cljs/core.cljs | 14 +++++++++-----
 1 file changed, 9 insertions(+), 5 deletions(-)

diff --git a/src/main/cljs/cljs/core.cljs b/src/main/cljs/cljs/core.cljs
index 3515da790..c86d105b6 100644
--- a/src/main/cljs/cljs/core.cljs
+++ b/src/main/cljs/cljs/core.cljs
@@ -12603,15 +12603,19 @@ reduces them without incurring seq initialization"
     (let [k (if-not (keyword? k) k (keyword->obj-map-key k))]
       (if (string? k)
         (if-not (nil? (scan-array 1 k strkeys))
-          (let [new-strobj (obj-clone strobj strkeys)]
-            (gobject/set new-strobj k v)
-            (ObjMap. meta strkeys new-strobj nil))             ;overwrite
-          (let [new-strobj (obj-clone strobj strkeys)          ; append
+          (if (identical? v (gobject/get strobj k))
+            coll
+            ;; overwrite
+            (let [new-strobj (obj-clone strobj strkeys)]
+              (gobject/set new-strobj k v)
+              (ObjMap. meta strkeys new-strobj nil))) 
+          ;; append
+          (let [new-strobj (obj-clone strobj strkeys) 
                 new-keys (aclone strkeys)]
             (gobject/set new-strobj k v)
             (.push new-keys k)
             (ObjMap. meta new-keys new-strobj nil)))
-        ; non-string key. game over.
+        ;; non-string key. game over.
         (-with-meta
           (-kv-reduce coll
             (fn [ret k v]

From 6b453ef5e5210bc298605dc4f18ccdaf23cc16ec Mon Sep 17 00:00:00 2001
From: davidnolen <david.nolen@gmail.com>
Date: Sun, 19 Oct 2025 11:05:47 -0400
Subject: [PATCH 2/4] same treatment for HashMap and Set

---
 src/main/cljs/cljs/core.cljs | 15 ++++++++++-----
 1 file changed, 10 insertions(+), 5 deletions(-)

diff --git a/src/main/cljs/cljs/core.cljs b/src/main/cljs/cljs/core.cljs
index c86d105b6..a1edf1242 100644
--- a/src/main/cljs/cljs/core.cljs
+++ b/src/main/cljs/cljs/core.cljs
@@ -12816,10 +12816,12 @@ reduces them without incurring seq initialization"
               i (scan-array-equiv 2 k new-bucket)]
           (aset new-hashobj h new-bucket)
           (if (some? i)
-            (do
-              ; found key, replace
-              (aset new-bucket (inc i) v)
-              (HashMap. meta count new-hashobj nil))
+            (if (identical? v (aget new-bucket (inc i)))
+              coll
+              (do
+                ; found key, replace
+                (aset new-bucket (inc i) v)
+                (HashMap. meta count new-hashobj nil)))
             (do
               ; did not find key, append
               (.push new-bucket k v)
@@ -12958,7 +12960,10 @@ reduces them without incurring seq initialization"
 
   ICollection
   (-conj [coll o]
-    (Set. meta (assoc hash-map o o) nil))
+    (let [new-hash-map (assoc hash-map o o)]
+      (if (identical? new-hash-map hash-map)
+        coll
+        (Set. meta new-hash-map nil))))
 
   IEmptyableCollection
   (-empty [coll] (with-meta (. Set -EMPTY) meta))

From 38f93afcbaf9245db7c2260a0a843266a28315ee Mon Sep 17 00:00:00 2001
From: davidnolen <david.nolen@gmail.com>
Date: Sun, 19 Oct 2025 11:07:22 -0400
Subject: [PATCH 3/4] tweak

---
 src/main/cljs/cljs/core.cljs | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/src/main/cljs/cljs/core.cljs b/src/main/cljs/cljs/core.cljs
index a1edf1242..3beaa425c 100644
--- a/src/main/cljs/cljs/core.cljs
+++ b/src/main/cljs/cljs/core.cljs
@@ -12605,17 +12605,17 @@ reduces them without incurring seq initialization"
         (if-not (nil? (scan-array 1 k strkeys))
           (if (identical? v (gobject/get strobj k))
             coll
-            ;; overwrite
+            ; overwrite
             (let [new-strobj (obj-clone strobj strkeys)]
               (gobject/set new-strobj k v)
               (ObjMap. meta strkeys new-strobj nil))) 
-          ;; append
+          ; append
           (let [new-strobj (obj-clone strobj strkeys) 
                 new-keys (aclone strkeys)]
             (gobject/set new-strobj k v)
             (.push new-keys k)
             (ObjMap. meta new-keys new-strobj nil)))
-        ;; non-string key. game over.
+        ; non-string key. game over.
         (-with-meta
           (-kv-reduce coll
             (fn [ret k v]

From df4a48b71faf6466e752df2aeea6d9bf8c64e2af Mon Sep 17 00:00:00 2001
From: davidnolen <david.nolen@gmail.com>
Date: Sun, 19 Oct 2025 11:21:27 -0400
Subject: [PATCH 4/4] add some unit tests

---
 src/test/cljs/cljs/lite_collections_test.cljs | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/src/test/cljs/cljs/lite_collections_test.cljs b/src/test/cljs/cljs/lite_collections_test.cljs
index 16d0296c1..a96148f00 100644
--- a/src/test/cljs/cljs/lite_collections_test.cljs
+++ b/src/test/cljs/cljs/lite_collections_test.cljs
@@ -28,6 +28,14 @@
   (= 1 (aget (clj->js (obj-map :x 1)) "x"))
   (= 1 (aget (clj->js {:x 1}) "x")))
 
+(deftest test-unchanged-identical?
+  (let [m (obj-map :foo 1)]
+    (identical? m (assoc m :foo 1)))
+  (let [m (simple-hash-map :foo 1)]
+    (identical? m (assoc m :foo 1)))
+  (let [s (simple-set [:foo])]
+    (identical? s (conj s :foo))))
+
 (comment
 
   (require '[cljs.lite-collections-test] :reload)