Fix lazy-loop's support for destructured bindings

Author: amalloy

src/flatland/useful/seq.clj

@@ -117,10 +117,11 @@
   need any laziness."
   [bindings & body]
   (let [f 'lazy-recur
-        [names values] (alternates bindings)]
-    `(letfn [(~f [~@names]
+        [names values] (alternates bindings)
+        blob-names (repeatedly (count names) gensym)]
+    `(letfn [(~f [~@blob-names]
                (lazy-seq
-                 (iter# ~@names)))
+                 (iter# ~@blob-names)))
              (iter# [~@names]
                ~@body)]
        (~f ~@values))))

test/flatland/useful/seq_test.clj

@@ -98,7 +98,14 @@
   (testing "0-arg lazy-loop"
     (is (= [1 1 1] (take 3
                          (lazy-loop []
-                           (cons 1 (lazy-recur))))))))
+                           (cons 1 (lazy-recur)))))))
+  (testing "destructuring support"
+    (is (= (range 1 6)
+           ((fn my-map [f xs] (lazy-loop [[x & xs :as coll] xs]
+                                (when (seq coll)
+                                  (cons (f x)
+                                        (lazy-recur xs)))))
+            inc (range 5))))))
 
 (deftest test-alternates
   (is (= '[[a b] [1 2]]