;;; missimetry of cons and bracketed list
(cons 16 (list 1 2 3))
(cons (list 1 2 3) 5)

;; so adding to front is easy,
;; adding to back is hard, since last element connected to nil

(last `(1 2 3 4))                       ; => (4)

;; for sets:
;; member, union, intersection, set-difference, subsetp

;; stopped at exercise 6.26 (i remember reading that in the court hallway)

;;; tables / alists

(setf words '((one un)
              (two deu)
              (three trois)
              (four quatre)
              (five cing)))

(assoc 'three words)
(cdr '(one un))
(rassoc '(un) words)                    ; why not found?

(setf sounds '((cow . moo)
               (pig . oink)
               (cat . meow)
               (dog . woof)
               (bird . tweet)))

(rassoc 'moo sounds)

;;; keyword arguments...
(setf text `(b a n a n a - p a n d a))
text

(remove `a text)
(remove `a text :count 3)
(remove `a text :count 2 :from-end t)

;; keyword is symbol with : at the start of the name
(keywordp ':hello)
(keywordp :hello)                       ; no need to quote?
(keywordp 'hello)

;; trees, subst & sublis ?
;; performing substitutions from alist into tree (?)
;;; subst - substitute X for Y in Z
(subst 'the 'a '(a list even nested (a hare) will get a substitution))

;;; sublis - takes make substitutions at same time
;; and it takes which? alisp plist? urgh
;; in emacs - plist is one level list
;; alist - list of cons cells
;; here also 2 level list is alist, and what's expected
(sublis '((rose . red) (violet . blue) (sunflower . yellow))
        '(here is the rose strucure (another rose and violet thingy) multilevel))

;; I suppse could be used on "code as data"