update if-let

Fixes #1189
janet-lang · Jun 11, 2023 · 42d76c9 · 42d76c9
1 parent 7272f43
commit 42d76c9
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Showing 2 changed files with 6 additions and 1 deletion.
diff --git a/src/boot/boot.janet b/src/boot/boot.janet
@@ -674,7 +674,11 @@
       (do
         (def bl (in bindings i))
         (def br (in bindings (+ 1 i)))
-        (tuple 'if (tuple 'def bl br) (aux (+ 2 i)) fal))))
+        (if (idempotent? bl)
+          (tuple 'if (tuple 'def bl br) (aux (+ 2 i)) fal)
+          (tuple 'if (tuple 'def (def sym (gensym)) br)
+                 (tuple 'upscope (tuple 'def bl sym) (aux (+ 2 i)))
+                 fal)))))
   (aux 0))
 
 (defmacro when-let

diff --git a/test/suite-boot.janet b/test/suite-boot.janet
@@ -129,6 +129,7 @@
 (assert (= (if-let [a my-array k (next a 5)] :t :f) :f) "if-let 4")
 (assert (= (if-let [[a b] my-array] a) 1) "if-let 5")
 (assert (= (if-let [{:a a :b b} {:a 1 :b 2}] b) 2) "if-let 6")
+(assert (= (if-let [[a b] nil] :t :f) :f) "if-let 7")
 
 (assert (= 14 (sum (map inc @[1 2 3 4]))) "sum map")
 (def myfun (juxt + - * /))