Day 3: Use Racket's `in-slice` instead of custom `chunks-of`.

lib.rkt

@@ -260,15 +260,6 @@
 (define (mmap f lst)
   (map (∂ map f) lst))
 
-;; chunks-of : (listof any) -> nonzero? -> (listof (listof any))
-;; Partitions a list into lists of the given size in order,
-;; with the final list possibly being smaller
-;; e.g. '(1 2 3 4 5) 2 => '((1 2) (3 4) (5))
-(define (chunks-of lst size)
-  (if (< (length lst) size) lst
-      (cons (take lst size)
-            (chunks-of (drop lst size) size))))
-
 ;; transpose : (listof (listof any)) -> (listof (listof any))
 ;; Turns a list of lists into a list of lists of
 ;; the first elements of the lists, ..., the nth elements

src/03.rkt

@@ -26,7 +26,7 @@
     (priority (unique rucksack))))
 
 (define part2
-  (for/sum ([rucksacks (chunks-of input 3)])
+  (for/sum ([rucksacks (in-slice 3 input)])
     (priority (badge rucksacks))))
 
 (show-solution part1 part2)