handle paramsneededpath with 0 params (used for params-reset) correctly in higher order paths

src/clj/com/rpl/specter/impl.cljx

@@ -123,6 +123,8 @@
       (com.rpl.specter.impl/bind-params* this a 0))
     ))
 
+(defn params-needed-path? [o]
+  (instance? ParamsNeededPath o))
 
 (defn bind-params* [^ParamsNeededPath params-needed-path params idx]
   (->CompiledPath

src/clj/com/rpl/specter/macros.clj

@@ -79,6 +79,10 @@
     `(let [paths# (map comp-paths* ~paths-seq)
            needed-params# (map num-needed-params paths#)
            offsets# (cons 0 (reductions + needed-params#))
+           any-params-needed?# (->> paths#
+                                    (filter params-needed-path?)
+                                    empty?
+                                    not)
            ~num-params-sym (last offsets#)
            ~latefns-sym (map
                           (fn [o# p#]
@@ -93,7 +97,7 @@
            ~@pre-bindings
            ret# ~(builder post-bindings num-params-sym impls)
            ]
-    (if (= 0 ~num-params-sym)
+    (if (not any-params-needed?#)
       (bind-params* ret# nil 0)
       ret#
       ))))

test/com/rpl/specter/core_test.cljx

@@ -642,6 +642,22 @@
   (is (= {3 21 4 31} (s/transform [s/ALL s/ALL] inc {2 20 3 30})))
   )
 
+(declarepath NestedHigherOrderWalker [k])
+
+(providepath NestedHigherOrderWalker
+  (s/if-path vector?
+    (s/if-path [s/FIRST (paramsfn [k] [e] (= k e))]
+      (s/continue-then-stay s/ALL (s/params-reset NestedHigherOrderWalker))
+      [s/ALL (s/params-reset NestedHigherOrderWalker)]
+      )))
+
+(deftest nested-higher-order-walker-test
+  (is (= [:q [:abc :I 3] [:ccc [:abc :I] [:abc :I "a" [:abc :I [:abc :I [:d]]]]]]
+         (s/setval [(NestedHigherOrderWalker :abc) (s/srange 1 1)]
+                   [:I]
+                   [:q [:abc 3] [:ccc [:abc] [:abc "a" [:abc [:abc [:d]]]]]]
+                   ))))
+
 #+clj
 (deftest large-params-test
   (let [path (apply s/comp-paths (repeat 25 s/keypath))