From d7f3a2042308ada08d4504ad1d6c2f82177dd815 Mon Sep 17 00:00:00 2001
From: Cam Saul <1455846+camsaul@users.noreply.github.com>
Date: Tue, 3 Jan 2023 18:37:14 -0800
Subject: [PATCH] Fix `merge` for an Instance (workaround for
 https://github.com/clj-commons/potemkin/issues/70) (#46)

---
 .dir-locals.el                 |  1 +
 src/toucan2/instance.clj       | 16 ++++++++++++++++
 src/toucan2/magic_map.clj      |  2 +-
 test/toucan2/instance_test.clj |  7 +++++++
 4 files changed, 25 insertions(+), 1 deletion(-)

diff --git a/.dir-locals.el b/.dir-locals.el
index 900a8a9..ba143a9 100644
--- a/.dir-locals.el
+++ b/.dir-locals.el
@@ -9,5 +9,6 @@
                   (eval . (put 'p/def-map-type 'clojure-doc-string-elt 2))
                   (eval . (put-clojure-indent 'p/defprotocol+ '(1 (:defn))))
                   (eval . (put-clojure-indent 'p/def-map-type '(2 nil nil (:defn))))
+                  (eval . (put-clojure-indent 'p/deftype+ '(2 nil nil (:defn))))
                   (eval . (put-clojure-indent 'with-meta '(:form)))
                   (eval . (put-clojure-indent 'with-bindings* '(:form))))))
diff --git a/src/toucan2/instance.clj b/src/toucan2/instance.clj
index 9c03798..a262f7b 100644
--- a/src/toucan2/instance.clj
+++ b/src/toucan2/instance.clj
@@ -67,6 +67,22 @@
       (Instance. model orig m new-meta)))
 
   clojure.lang.IPersistentCollection
+  (cons [this o]
+    (cond
+      (map? o)
+      (reduce #(apply assoc %1 %2) this o)
+
+      (clojure.core/instance? java.util.Map o)
+      (reduce
+       #(apply assoc %1 %2)
+       this
+       (into {} o))
+
+      :else
+      (if-let [[k v] (seq o)]
+        (assoc this k v)
+        this)))
+
   (equiv [_this another]
     (cond
       (clojure.core/instance? toucan2.protocols.IModel another)
diff --git a/src/toucan2/magic_map.clj b/src/toucan2/magic_map.clj
index d7d7db3..8adcdd1 100644
--- a/src/toucan2/magic_map.clj
+++ b/src/toucan2/magic_map.clj
@@ -30,7 +30,7 @@
   "The default magic map transform function. Converts things to `kebab-case`, preserving namespaces."
   [k]
   (when k
-    (if (and (clojure.core/instance? clojure.lang.Named k) (namespace k))
+    (if (and (instance? clojure.lang.Named k) (namespace k))
       (keyword (->kebab-case (namespace k)) (->kebab-case (name k)))
       (keyword (->kebab-case (name k))))))
 
diff --git a/test/toucan2/instance_test.clj b/test/toucan2/instance_test.clj
index f2d3847..c6da039 100644
--- a/test/toucan2/instance_test.clj
+++ b/test/toucan2/instance_test.clj
@@ -411,3 +411,10 @@
                empty-instance))
         (is (instance/instance? empty-instance))
         (is (instance/instance-of? ::venues empty-instance))))))
+
+(deftest ^:parallel merge-test
+  (let [m (instance/instance ::birds {:name "Parroty"})]
+    (are [m2 expected] (= expected
+                          (merge m m2))
+      {:type :parakeet} {:name "Parroty", :type :parakeet}
+      nil               {:name "Parroty"})))