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+;; https://adventofcode.com/2021/day/2
+
+; optional -- 'sum' is more visually indicative than 'apply +'
+(func sum (nums) (apply + nums))
+
+(func do-the-thing (inp)
+    ; order doesn't matter, so we can split horizontal and vertical
+    ; movement without affecting the answer
+    (def vert-changes (filter (lambda (x) (in? (first x) (list "up" "down"))) inp))
+    (def horiz-changes (filter (lambda (x) (eq? (first x) "forward")) inp))
+
+    ; turn "up"/"down" into +/- 1 
+    (def vert-numbers
+        (map
+            (lambda (x)
+                (if (eq? (first x) "up")
+                    (prepend (rest x) (- 1))
+                    (prepend (rest x) 1)))
+            vert-changes))
+
+    (def vert
+        (sum ; add everything up
+            (map
+                (lambda (x) (* (first x) (last x))) ; multiply each pair together
+                vert-numbers)))
+
+    (def horiz
+        (sum
+            (map last horiz-changes))) ; we know there's only 2 elements in each list, and we want the last one
+
+    (print (concat "vert: " (->string vert)))
+    (print (concat "horiz: " (->string horiz)))
+    (* vert horiz))
+
+(def lines 
+    (map
+        (lambda (x) (list (first x) (string->int (first (rest x))))) ; convert second values to int
+        (map 
+            (lambda (x) (split x " "))
+            (map strip
+                (read-lines "input.txt")))))
+
+(print (->string lines))
+(print (->string (do-the-thing lines)))