Add -iota (#207)

dash.el

@@ -2154,6 +2154,23 @@ N is the length of the returned list."
         (push (funcall fun (car r)) r))
       (nreverse r))))
 
+(defun -iota (count &optional start step)
+  "Return a list containing COUNT numbers.
+Starts from START and adds STEP each time.  The default START is
+zero, the default STEP is 1.
+This function takes its name from the corresponding primitive in
+the APL language."
+  (if (or (not (integerp count)) (< count 0))
+      (signal 'wrong-type-argument count))
+  (if (and step (zerop step)) (make-list count start)
+    (let ((res '())
+          (x (or start 0))
+          (dx (or step 1)))
+      (while (<= 0 (setq count (1- count)))
+        (push x res)
+        (setq x (+ x dx)))
+      (nreverse res))))
+
 (defun -fix (fn list)
   "Compute the (least) fixpoint of FN with initial input LIST.
 

dev/examples.el

@@ -614,6 +614,10 @@ new list."
     (-interleave '(1 2 3) '("a" "b")) => '(1 "a" 2 "b")
     (-interleave '(1 2 3) '("a" "b" "c" "d")) => '(1 "a" 2 "b" 3 "c"))
 
+  (defexamples -iota
+    (-iota 6) => '(0 1 2 3 4 5)
+    (-iota 4 2.5 -2) => '(2.5 0.5 -1.5 -3.5))
+
   (defexamples -zip-with
     (-zip-with '+ '(1 2 3) '(4 5 6)) => '(5 7 9)
     (-zip-with 'cons '(1 2 3) '(4 5 6)) => '((1 . 4) (2 . 5) (3 . 6))