最早的时候，是从emacs听说lisp的，不过emacs这等神器，却并非我的菜，几经折腾最终滚回了简洁的vim。
最早开始学习lisp，是跟着田春译的《实用common lisp编程》，看了几章越看越累，等到看到讲单元测试那章时，我已经不知道在讲什么了。不过很惊叹lisp自动生成程序的能力倒是，还有种让人着迷的数学感。
后来看见网上有人在译ansi common lisp中文版，沉寂了两个月的lisp情怀陡升，我又开始看了。看了两章也陷入了越看越累的境地，最后到了能读懂却不能写出的境界，相对之前，也算是进步吧。然而才到高级数据结构那部分，我已没看下去的勇气，我觉得自己这种小白应该先修炼本更循序渐进的。
然后找啊找在common-lisp上有推荐Land of lisp这本书,虽然很贵，但天朝的孩子们总是有办法的：lisp资料。
好难得有本图文并茂的书，声称一次一个游戏，我就喜欢这种例子丰富的东西，幽默点不致于无聊更好。找不到中文版，算了，英文版直接上吧。话说还考研，唉，还是想抽空看看这个。
猜数的小游戏，不解释。
(defun guess-my-number ()
(ash (+ *big* *small*) -1))
(defun bigger ()
(setf *small* (1+ (guess-my-number)))
(guess-my-number))
(defun smaller ()
(setf *big* (1- (guess-my-number)))
(guess-my-number))
(defun start-over ()
(defparameter *small* 1)
(defparameter *big* 100)
(guess-my-number));;定义节点及描述
(defparameter *nodes* '((living-room (you are in the living-room.
a wizard is snoring loudly on the couch.))
(garden (you are in a beautiful garden.
there is a well in front of you.))
(attic (you are in the attic.
there is a giant welding torch in the corner.))))
;;定义描述效应位置的函数
(defun describe-location (location nodes)
(cadr (assoc location nodes)))
;;定义节点-路径
(defparameter *edges* '((living-room (garden west door)
(attic upstairs ladder))
(garden (living-room east door))
(attic (living-room downstairs ladder))))
;;定义描述路径函数
(defun describe-path (edge)
`(there is a ,(caddr edge) going ,(cadr edge) from here.))
;;定义描述对应位置路径的函数
(defun describe-paths (location edges)
(apply #'append (mapcar #'describe-path (cdr (assoc location edges)))))
;;定义物品列表
(defparameter *objects* '(whiskey bucket frog chain))
;;物品-位置对，hash？
(defparameter *object-locations* '((whiskey living-room)
(bucket living-room)
(chain garden)
(frog garden)))
;;得到相应位置物品列表
(defun objects-at (loc objs obj-locs)
(labels ((at-loc-p (obj)
(eq (cadr (assoc obj obj-locs)) loc)))
(remove-if-not #'at-loc-p objs)))
;;描述相应位置物品
(defun describe-objects (loc objs obj-loc)
(labels ((describe-obj (obj)
`(you see a ,obj on the floor.)))
(apply #'append (mapcar #'describe-obj (objects-at loc objs obj-loc)))))
;;给定初始位置
(defparameter *location* 'living-room)
;;定义查看函数
(defun look ()
(append (describe-location *location* *nodes*)
(describe-paths *location* *edges*)
(describe-objects *location* *objects* *object-locations*)))
;;定义行走函数
(defun walk (direction)
(let ((next (find direction
(cdr (assoc *location* *edges*))
:key #'cadr)))
(if next
(progn (setf *location* (car next))
(look))
'(you cannot go that way.))))
;;定义拾起函数
(defun pickup (object)
(cond ((member object
(objects-at *location* *objects* *object-locations*))
(push (list object 'body) *object-locations*)
`(you are now carrying the ,object))
(t '(you cannot get that.))))
;;查看现有物品的函数
(defun inventory ()
(cons 'items- (objects-at 'body *objects* *object-locations*)))
;;登入界面
(defun say-hello ()
(princ "Please type your name:")
(let ((name (read-line)))
(princ "Nice to meet you, ")
(princ name)))
;;自定义repl
(defun game-repl ()
(let ((cmd (game-read)))
(unless (eq (car cmd) 'quit)
(game-print (game-eval cmd))
(game-repl))))
;;自定义的read
(defun game-read ()
(let ((cmd (read-from-string
(concatenate 'string "(" (read-line) ")"))))
(flet ((quote-it (x)
(list 'quote x)))
(cons (car cmd) (mapcar #'quote-it (cdr cmd))))))
;;给定可执行命令
(defparameter *allowed-commands* '(look walk pickup inventory))
;;自定义eval
(defun game-eval (sexp)
(if (member (car sexp) *allowed-commands*)
(eval sexp)
'(i do not know that command.)))
;;转换字符列表大小写函数
(defun tweak-text (lst caps lit)
(when lst
(let ((item (car lst))
(rest (cdr lst)))
(cond ((eq item #\space) (cons item (tweak-text rest caps lit)))
((member item '(#\! #\? #\.)) (cons item (tweak-text rest t lit)))
((eq item #\") (tweak-text rest caps (not lit)))
(lit (cons item (tweak-text rest nil lit)))
((or caps lit) (cons (char-upcase item) (tweak-text rest nil lit)))
(t (cons (char-downcase item) (tweak-text rest nil nil)))))))
;;自定义print
(defun game-print (lst)
(princ (coerce (tweak-text (coerce (string-trim "() "
(prin1-to-string lst))
'list)
t
nil)
'string))
(fresh-line))然后测试游戏引擎，在repl中输入
(game-repl)首先让我惊异的就repl可以自定义,还有那个quasiquote很好用。
然后学到了以下一堆命令：