hy.contrib.walk: Add support for walking cons cells

Signed-off-by: Gergely Nagy <algernon@madhouse-project.org>

hy/contrib/walk.hy

@@ -32,6 +32,9 @@
     (outer (HyExpression (map inner form)))]
    [(instance? HyDict form)
     (HyDict (outer (HyExpression (map inner form))))]
+   [(cons? form)
+    (outer (cons (inner (first form))
+                 (inner (rest form))))]
    [(instance? list form)
     ((type form) (outer (HyExpression (map inner form))))]
    [true (outer form)]))

tests/native_tests/contrib/walk.hy

@@ -3,6 +3,7 @@
 (def walk-form '(print {"foo" "bar"
                         "array" [1 2 3 [4]]
                         "something" (+ 1 2 3 4)
+                        "cons!" (cons 1 2)
                         "quoted?" '(foo)}))
 
 (defn collector [acc x]