diff --git a/lib/lib-advent.org b/lib/lib-advent.org
index 62ce6af..b8c8e87 100644
--- a/lib/lib-advent.org
+++ b/lib/lib-advent.org
@@ -38,22 +38,42 @@
                                                (-map-indexed (lambda (x el) (list el (list x y))) l))
                                              li)))))
   #+end_src
+
 * 2D geometry auxiliary functions
   Here a vector is just a list with two components; the "dot"
   function is a bit of an overkill tbh
 
   #+begin_src emacs-lisp :results none
-  (defun advent/dot (a b)
-    "Return the dot product of the two vectors"
-    (-reduce #'+ (-map (lambda (x) (* (car x) (cdr x))) (-zip-pair a b))))
-
-  (defun advent/neighbour (p dir)
-    "Returns the neighbour to P in the direction DIR"
-    (list (+ (car p) (car dir))
-          (+ (cadr p) (cadr dir))))
-
-  (defun advent/taxicab-distance (p q)
-    "Returns the taxicab distance from P to Q"
-    (+ (abs (- (car p) (car q)))
-       (abs (- (cadr p) (cadr q)))))
-#+end_src
+    (defun advent/dot (a b)
+      "Return the dot product of the two vectors"
+      (-reduce #'+ (-map (lambda (x) (* (car x) (cdr x))) (-zip-pair a b))))
+
+    (defun advent/neighbour (p dir)
+      "Returns the neighbour to P in the direction DIR"
+      (list (+ (car p) (car dir))
+            (+ (cadr p) (cadr dir))))
+
+    (defun advent/taxicab-distance (p q)
+      "Returns the taxicab distance from P to Q"
+      (+ (abs (- (car p) (car q)))
+         (abs (- (cadr p) (cadr q)))))
+       #+end_src
+
+  These are two-dimensional equivalent of -map and -map-indexed
+  #+begin_src emacs-lisp
+    (defun -2map (fun li)
+      (--map (-map fun it) li))
+
+    (defmacro --2map (form list)
+      `(-2map (lambda (it) ,form) ,list))
+
+    (defun -2map-indexed (fun li)
+      (-map-indexed (lambda (j row)
+                      (-map-indexed (lambda (i it)
+                                      (funcall fun i j it))
+                                    row))
+                    li))
+
+    (defmacro --2map-indexed (form li)
+      `(-2map-indexed (lambda (it-index-1 it-index-2 it) ,form) ,li))
+  #+end_src