Merge pull request #242 from magnars/fix-infinite-loop-zip-interleave

Fix infinite loop in -zip/-interleave when called with no arguments.

dash.el

@@ -1104,11 +1104,12 @@ elements of LIST.  Keys are compared by `equal'."
 (defun -interleave (&rest lists)
   "Return a new list of the first item in each list, then the second etc."
   (declare (pure t) (side-effect-free t))
-  (let (result)
-    (while (-none? 'null lists)
-      (--each lists (!cons (car it) result))
-      (setq lists (-map 'cdr lists)))
-    (nreverse result)))
+  (when lists
+    (let (result)
+      (while (-none? 'null lists)
+        (--each lists (!cons (car it) result))
+        (setq lists (-map 'cdr lists)))
+      (nreverse result))))
 
 (defmacro --zip-with (form list1 list2)
   "Anaphoric form of `-zip-with'.
@@ -1150,16 +1151,17 @@ of cons cells. Otherwise, return the groupings as a list of lists.
 Please note! This distinction is being removed in an upcoming 3.0
 release of Dash. If you rely on this behavior, use -zip-pair instead."
   (declare (pure t) (side-effect-free t))
-  (let (results)
-    (while (-none? 'null lists)
-      (setq results (cons (mapcar 'car lists) results))
-      (setq lists (mapcar 'cdr lists)))
-    (setq results (nreverse results))
-    (if (= (length lists) 2)
-        ;; to support backward compatability, return
-        ;; a cons cell if two lists were provided
-        (--map (cons (car it) (cadr it)) results)
-      results)))
+  (when lists
+    (let (results)
+      (while (-none? 'null lists)
+        (setq results (cons (mapcar 'car lists) results))
+        (setq lists (mapcar 'cdr lists)))
+      (setq results (nreverse results))
+      (if (= (length lists) 2)
+          ;; to support backward compatability, return
+          ;; a cons cell if two lists were provided
+          (--map (cons (car it) (cadr it)) results)
+        results))))
 
 (defalias '-zip-pair '-zip)
 

dev/examples.el

@@ -645,7 +645,8 @@ new list."
     (-interleave '(1 2) '("a" "b")) => '(1 "a" 2 "b")
     (-interleave '(1 2) '("a" "b") '("A" "B")) => '(1 "a" "A" 2 "b" "B")
     (-interleave '(1 2 3) '("a" "b")) => '(1 "a" 2 "b")
-    (-interleave '(1 2 3) '("a" "b" "c" "d")) => '(1 "a" 2 "b" 3 "c"))
+    (-interleave '(1 2 3) '("a" "b" "c" "d")) => '(1 "a" 2 "b" 3 "c")
+    (-interleave) => nil)
 
   (defexamples -zip-with
     (-zip-with '+ '(1 2 3) '(4 5 6)) => '(5 7 9)
@@ -657,7 +658,8 @@ new list."
     (-zip '(1 2 3) '(4 5 6 7)) => '((1 . 4) (2 . 5) (3 . 6))
     (-zip '(1 2 3 4) '(4 5 6)) => '((1 . 4) (2 . 5) (3 . 6))
     (-zip '(1 2 3) '(4 5 6) '(7 8 9)) => '((1 4 7) (2 5 8) (3 6 9))
-    (-zip '(1 2) '(3 4 5) '(6)) => '((1 3 6)))
+    (-zip '(1 2) '(3 4 5) '(6)) => '((1 3 6))
+    (-zip) => nil)
 
   (defexamples -zip-fill
     (-zip-fill 0 '(1 2 3 4 5) '(6 7 8 9)) => '((1 . 6) (2 . 7) (3 . 8) (4 . 9) (5 . 0)))