!map macro

bang.el

@@ -32,11 +32,25 @@
 It should only be set using dynamic scope with a let, like:
 (let ((!compare-fn =)) (!union numbers1 numbers2 numbers3)")
 
+(defmacro !filter (form-or-fn list)
+  `(let ((!--list ,list)
+         (!--result '()))
+     (while !--list
+       (let ((it (car !--list)))
+         (when ,(if (functionp form-or-fn) (list form-or-fn 'it) (list 'progn form-or-fn))
+           (setq !--result (cons it !--result))))
+       (setq !--list (cdr !--list)))
+     (nreverse !--result)))
+
+(defmacro !map (form-or-fn list)
+  (if (functionp form-or-fn)
+      `(mapcar #',form-or-fn ,list)
+    `(mapcar #'(lambda (it) ,form-or-fn) ,list)))
+
+
 (defun !concat (list)
   (apply 'concatenate 'list list))
 
-(defalias '!map 'mapcar)
-
 (defalias '!select 'remove-if-not)
 (defalias '!reject 'remove-if)
 
@@ -45,16 +59,6 @@ It should only be set using dynamic scope with a let, like:
 (defun !mapcat (fn list)
   (!concat (!map fn list)))
 
-(defmacro !filter (form-or-fn list)
-  `(let ((!--list ,list)
-         (!--result '()))
-     (while !--list
-       (let ((it (car !--list)))
-         (when ,(if (functionp form-or-fn) (list form-or-fn 'it) (list 'progn form-or-fn))
-           (setq !--result (cons it !--result))))
-       (setq !--list (cdr !--list)))
-     (nreverse !--result)))
-
 (defun !uniq (list)
   "Return a new list with all duplicates removed.
 The test for equality is done with `equal',

tests.el

@@ -2,6 +2,7 @@
 (require 'bang)
 
 (defun even? (num) (= 0 (% num 2)))
+(defun square (num) (* num num))
 
 (ert-deftest filter ()
   "`!filter' returns a new list of only those elements where the predicate was non-nil."
@@ -9,6 +10,12 @@
   (should (equal (!filter (= 0 (% it 2)) '(1 2 3 4)) '(2 4)))
   (should (equal (!filter even? '(1 2 3 4)) '(2 4))))
 
+(ert-deftest map ()
+  "`!map' returns a new list with the results of calling the function on each element."
+  (should (equal (!map (lambda (num) (* num num)) '(1 2 3 4)) '(1 4 9 16)))
+  (should (equal (!map (* it it) '(1 2 3 4)) '(1 4 9 16)))
+  (should (equal (!map square '(1 2 3 4)) '(1 4 9 16))))
+
 (ert-deftest difference ()
   "`!difference' returns a new list of only elements in list1 that are not in list2."
   (should (equal (!difference '() '()) '()))