Running sum and product can only be computed from non-empty lists

dash.el

@@ -2222,9 +2222,13 @@ Return nil if N is less than 1."
   (apply '+ list))
 
 (defun -running-sum (list)
-  "Return a list with running sums of items in LIST."
+  "Return a list with running sums of items in LIST.
+
+LIST must be non-empty."
   (declare (pure t) (side-effect-free t))
-  (-map '-sum (-inits list)))
+  (unless (consp list)
+    (error "LIST must be non-empty"))
+  (-reductions '+ list))
 
 (defun -product (list)
   "Return the product of LIST."
@@ -2232,9 +2236,13 @@ Return nil if N is less than 1."
   (apply '* list))
 
 (defun -running-product (list)
-  "Return a list with running products of items in LIST."
+  "Return a list with running products of items in LIST.
+
+LIST must be non-empty."
   (declare (pure t) (side-effect-free t))
-  (-map '-product (-inits list)))
+  (unless (consp list)
+    (error "LIST must be non-empty"))
+  (-reductions '* list))
 
 (defun -max (list)
   "Return the largest value from LIST of numbers or markers."

dev/examples.el

@@ -363,9 +363,9 @@ new list."
     (-sum '(1 2 3 4)) => 10)
 
   (defexamples -running-sum
-    (-running-sum '()) => nil
+    (-running-sum '(1 2 3 4)) => '(1 3 6 10)
     (-running-sum '(1)) => '(1)
-    (-running-sum '(1 2 3 4)) => '(1 3 6 10))
+    (-running-sum '()) !!> error)
 
   (defexamples -product
     (-product '()) => 1
@@ -373,9 +373,9 @@ new list."
     (-product '(1 2 3 4)) => 24)
 
   (defexamples -running-product
-    (-running-product '()) => nil
+    (-running-product '(1 2 3 4)) => '(1 2 6 24)
     (-running-product '(1)) => '(1)
-    (-running-product '(1 2 3 4)) => '(1 2 6 24))
+    (-running-product '()) !!> error)
 
   (defexamples -min
     (-min '(0)) => 0