Inital commit for elisp version of kata

elisp/gilded-rose.el

@@ -0,0 +1,42 @@
+(defun make-item (name sell-in quality)
+  "Create an item with NAME, SELL-IN, and QUALITY."
+  (list :name name :sell-in sell-in :quality quality))
+
+(defun item-name (item)
+  "Return the name of ITEM."
+  (plist-get item :name))
+
+(defun item-sell-in (item)
+  "Return the sell-in value of ITEM."
+  (plist-get item :sell-in))
+
+(defun item-quality (item)
+  "Return the quality of ITEM."
+  (plist-get item :quality))
+
+(defun update-quality (item)
+  "Update the quality of the ITEM according to the Gilded Rose rules."
+  (let ((quality (item-quality item))
+        (sell-in (item-sell-in item)))
+    (cond
+     ;; Aged Brie
+     ((string= (item-name item) "Aged Brie")
+      (setf (nth 2 item) (min 50 (1+ quality))))
+     
+     ;; Backstage passes
+     ((string= (item-name item) "Backstage passes")
+      (cond
+       ((> sell-in 10) (setf (nth 2 item) quality))
+       ((and (<= sell-in 10) (> sell-in 5)) (setf (nth 2 item) (min 50 (+ quality 2))))
+       ((and (<= sell-in 5) (> sell-in 0)) (setf (nth 2 item) (min 50 (+ quality 3))))
+       (t (setf (nth 2 item) 0))))
+     
+     ;; Sulfuras
+     ((string= (item-name item) "Sulfuras")
+      (setf (nth 2 item) quality)) ;; Sulfuras never changes
+
+
+     (defvar fork (make-item "fork" 10 10))
+     (update-quality fork)
+     (item-quality fork)
+(provide 'gilded-rose)