;;; constant timem to access

(make-array 5 :initial-element 1)
(make-array 6 :initial-contents `(a e i o u j)) ; should match with size
(make-array 3)                                  ; elements are implementation dependent

*print-array*

;;; hash tables - more performant, but a bit more complicated api than alist
(setf my-table (make-hash-table))
(gethash 'a my-table)
(setf (gethash 'a my-table) '(mary doctor))

;;; property list
;; (ind-1 value-1 ind-2 value-2 ...)
;; so all on one level instead of cons or lists
;; GET function retrieves values from property list of a symbol.
;; so first we put some properties to symbol
(setf (get 'fred 'sex) 'male)
(setf (get 'fred 'age) 33)
(get 'fred 'sex)
(describe 'fred)                        ; plist is printed in repl

(remprop 'fred 'age)

(symbol-plist 'fred)

(defun subprop (symbol item property)
  (setf (get symbol property)
        (remove item (get symbol property))))  ; well that's exercise for lisp properties, ok

(setf (get 'fred 'syblings) '(jeorge tom))
(get 'fred 'syblings)
(subprop 'fred 'tom 'syblings)

;; allright, let's do exercise about random and histogram
;;
;; (new-histogram 11)
;; (dotimes 200
;;  (record-value (random 11)))
;; (print-histogram)

(defvar *hist-array*)
(defvar *total-points*)

(defun new-histogram (size)
  (setf *hist-array* (make-array size :initial-element 0))
  (setf *total-points* 0))

(new-histogram 11)

(length *hist-array*)
(aref *hist-array* 1)
(incf (aref *hist-array* 1))

(defun record-value (n)
  "Adds value h to corresponding bucket of *HIST-ARRAY* and increases *TOTAL-POINTS*."
  (if (> n (length *hist-array*)) (error "nubmer is too big"))
  (incf (aref *hist-array* n))
  (incf *total-points*))

;; next - print

(defun print-hist-line (i)
  (let* ((hist-value (aref *hist-array* i))
         (hist-line (make-string hist-value :initial-element #\*)))
    (format t "~&~2S [ ~3S] ~S" i hist-value hist-line)))

(dotimes (i 200)
  (record-value (random (length *hist-array*))))

(print-hist-line 2)

(defun print-histogram ()
  (dotimes (i (length *hist-array*))
    (print-hist-line  i)))

(print-histogram)

;;; yay!