Fix some bugs in `ap-reduce`

NEWS.rst

@@ -36,6 +36,8 @@ Bug Fixes
 * Fixed crashes from inaccessible history files.
 * The unit tests no longer unintentionally import the internal Python module "test".
   This allows them to pass when run inside the "slim" Python Docker images.
+* `ap-reduce` now accepts any iterable.
+* `ap-reduce` now evaluates its arguments only once.
 
 Misc. Improvements
 ------------------------------

hy/extra/anaphoric.hy

@@ -91,12 +91,15 @@
        ~n)))
 
 
-(defmacro ap-reduce [form lst &optional [initial-value None]]
+(defmacro! ap-reduce [form o!lst &optional [initial-value None]]
   "Anaphoric form of reduce, `acc' and `it' can be used for a form"
   `(do
-     (setv acc ~(if (none? initial-value) `(get ~lst 0) initial-value))
-     (ap-each ~(if (none? initial-value) `(cut ~lst 1) lst)
-              (setv acc ~form))
+     (setv acc ~(if (none? initial-value)
+       `(do
+         (setv ~g!lst (iter ~g!lst))
+         (next ~g!lst))
+       initial-value))
+     (ap-each ~g!lst (setv acc ~form))
      acc))
 
 

tests/native_tests/extra/anaphoric.hy

@@ -64,7 +64,17 @@
   (assert (= (ap-reduce (* acc it) [1 2 3] 6) 36))
   (assert (= (ap-reduce (+ acc " on " it) ["Hy" "meth"])
               "Hy on meth"))
-  (assert (= (ap-reduce (+ acc it) [] 1) 1)))
+  (assert (= (ap-reduce (+ acc it) [] 1) 1))
+
+  ; https://github.com/hylang/hy/issues/1848
+  (assert (= (ap-reduce (* acc it) (map inc [1 2 3])) 24))
+  (assert (= (ap-reduce (* acc it) (map inc [1 2 3]) 4) 96))
+
+  (setv expr-evaluated 0)
+  (assert (=
+    (ap-reduce (* acc it) (do (+= expr-evaluated 1) [4 5 6])))
+    120)
+  (assert (= expr-evaluated 1)))
 
 (defn test-tag-fn []
   ;; test ordering