2 files changed, 49 insertions, 0 deletions
diff --git a/advent-of-code/2023/lib/obj.rkt b/advent-of-code/2023/lib/obj.rkt
new file mode 100644
index 0000000..9217976
--- /dev/null
+++ b/advent-of-code/2023/lib/obj.rkt
@@ -0,0 +1,32 @@
+#lang racket
+
+(provide obj-maker
+         obj-set
+         obj-show)
+
+(define (alist->obj alist)
+  (lambda key
+    (if (null? key)
+      alist
+      (cadr (assoc (car key) alist)))))
+
+(define (obj-maker . fields)
+  (lambda inits
+    (define alist (map list fields inits))
+    (alist->obj alist)))
+
+(define (obj-set record key value)
+  (define alist (record))
+  (define new-alist
+    (let loop ((new-list '()) (cur alist) (is-set #f))
+      (if (null? cur)
+        (if is-set
+          new-list
+          (cons (list key value) new-list))
+        (let ()
+          (if (eq? key (caar cur))
+            (loop (cons (list key value) new-list) (cdr cur) #t)
+            (loop (cons (car cur) new-list) (cdr cur) is-set))))))
+  (alist->obj new-alist))
+
+(define (obj-show x) (x))
+\ No newline at end of file
diff --git a/advent-of-code/2023/lib/utils.rkt b/advent-of-code/2023/lib/utils.rkt
new file mode 100644
index 0000000..946bb86
--- /dev/null
+++ b/advent-of-code/2023/lib/utils.rkt
@@ -0,0 +1,17 @@
+#lang racket
+
+(provide get-lines
+         enumerate)
+
+(define (get-lines fp)
+  (let loop ((lines '()))
+    (define l (read-line fp))
+    (if (eof-object? l)
+      (reverse lines)
+      (loop (cons l lines)))))
+
+(define (enumerate lst)
+  (let loop ((i 1) (ret '()) (remain lst))
+    (if (null? remain)
+      (reverse ret)
+      (loop (+ 1 i) (cons (list (car remain) i) ret) (cdr remain)))))
+\ No newline at end of file