From ed08d8878a2b4986547a2fb8c028f68292d5d87a Mon Sep 17 00:00:00 2001
From: David Nolen <david.nolen@gmail.com>
Date: Tue, 21 Jul 2026 15:42:17 -0400
Subject: [PATCH 1/2] port CLJ-2949: add req! (throwing get) and tests

Co-authored-by: Fogus <mefogus@gmail.com>
---
 src/main/cljs/cljs/core.cljs      | 10 ++++++++++
 src/test/cljs/cljs/core_test.cljs | 11 ++++++++++-
 2 files changed, 20 insertions(+), 1 deletion(-)

diff --git a/src/main/cljs/cljs/core.cljs b/src/main/cljs/cljs/core.cljs
index 993a5d5fe..2d1e9c599 100644
--- a/src/main/cljs/cljs/core.cljs
+++ b/src/main/cljs/cljs/core.cljs
@@ -2072,6 +2072,16 @@ reduces them without incurring seq initialization"
         :else not-found)
       not-found)))
 
+(def REQ_NOT_FOUND #js {})
+
+(defn req!
+  "Like arity-2 'get', but throws if key not present."
+  [m k]
+  (let [v (get m k REQ_NOT_FOUND)]
+    (if (identical? REQ_NOT_FOUND v)
+      (throw (js/Error. (str_ "Missing required key: " k)))
+      v)))
+
 (declare PersistentHashMap PersistentArrayMap MapEntry)
 
 (defn assoc
diff --git a/src/test/cljs/cljs/core_test.cljs b/src/test/cljs/cljs/core_test.cljs
index 8bff60d3b..933f87781 100644
--- a/src/test/cljs/cljs/core_test.cljs
+++ b/src/test/cljs/cljs/core_test.cljs
@@ -2012,4 +2012,13 @@
 
 (deftest test-cljs-3415
   (let [a 1 b 1]
-    (is (thrown? js/Error #{a b}))))
\ No newline at end of file
+    (is (thrown? js/Error #{a b}))))
+
+(deftest test-req!
+  (let [m {:a 1, :b 2, :f nil, :g false, nil "nil"}]
+    (is (thrown? js/Error (req! m :e)))
+    (are [x y] (= x y)
+         (req! m :a)  1
+         (req! m nil) "nil"
+         (req! m :b)  2
+         (req! m :f)  nil)))

From a24845975eed4c2d5c80cfb9532dec6f3777d3d9 Mon Sep 17 00:00:00 2001
From: David Nolen <david.nolen@gmail.com>
Date: Tue, 21 Jul 2026 15:50:34 -0400
Subject: [PATCH 2/2] make REQ_NOT_FOUND private

---
 src/main/cljs/cljs/core.cljs | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/main/cljs/cljs/core.cljs b/src/main/cljs/cljs/core.cljs
index 2d1e9c599..f97d4c7bc 100644
--- a/src/main/cljs/cljs/core.cljs
+++ b/src/main/cljs/cljs/core.cljs
@@ -2072,7 +2072,7 @@ reduces them without incurring seq initialization"
         :else not-found)
       not-found)))
 
-(def REQ_NOT_FOUND #js {})
+(def ^:private REQ_NOT_FOUND #js {})
 
 (defn req!
   "Like arity-2 'get', but throws if key not present."