support (global) in let

hy/contrib/walk.hy

@@ -170,7 +170,6 @@ as can nested let forms.
            (setv head (first form))
            (setv tail (cut form 1))
            (cond [(in head '[fn fn*])
-                  ;; TODO: handle globals, locals
                   (setv body (cut tail 1)
                         protected #{}
                         fn-bindings `[])
@@ -218,6 +217,9 @@ as can nested let forms.
                                                     form)))
                               identity
                               tail))]
+                 [(= head 'global)
+                  (.update protected-symbols (set tail))
+                  form]
                  [(in head '[import quote]) form]
                  [(= head 'defclass)
                   ;; don't expand the name of the class

tests/native_tests/contrib/walk.hy

@@ -293,6 +293,21 @@
   (assert (= 2 (+count)))
   (assert (= 42 (+count 40))))
 
-;; TODO
+(defn test-let-global []
-;; test-let-global
+  (setv (get (globals)
+             'let-global)
+        "global")
+  (let [let-global 1]
+       (assert (= let-global 1))
+       (defn foo []
+         (assert (= let-global 1))
+         (global let-global)
+         (assert (= let-global "global"))
+         (setv let-global "mutated")
+         (assert (= let-global "mutated")))
+       (foo)
+       (assert (= let-global 1))
+       (assert (= (get (globals)
+                       'let-global)
+                  "mutated"))))