evolution.lisp

(defparameter *width* 100)
(defparameter *height* 30)
(defparameter *jungle* '(45 10 10 10))
(defparameter *plant-energy* 80)

(defparameter *plants* (make-hash-table :test #'equal))

(defun random-plant (left top width height)
   (let ((pos (cons (+ left (random width)) (+ top (random height)))))
        (setf (gethash pos *plants*) t)))

(defun add-plants ()
   (apply #'random-plant *jungle*)
   (random-plant 0 0 *width* *height*))

(defstruct animal x y energy dir genes)

(defparameter *animals* 
    (list (make-animal :x      (ash *width*  -1)
                       :y      (ash *height* -1)
                       :energy 1000
                       :dir    0
                       :genes  (loop repeat 8
                                     collect (1+ (random 10)))))) ; Was "collecting"

(defun move (animal)
  (let ((dir (animal-dir animal))
        (x (animal-x animal))
        (y (animal-y animal)))
    (setf (animal-x animal) (mod (+ x
                                    (cond ((and (>= dir 2) (< dir 5)) 1)
                                          ((or (= dir 1) (= dir 5)) 0)
                                          (t -1))
                                    *width*)
                                 *width*))
    (setf (animal-y animal) (mod (+ y
                                    (cond ((and (>= dir 0) (< dir 3)) -1)
                                          ((and (>= dir 4) (< dir 7)) 1)
                                          (t 0))
                                    *height*)
                                 *height*))
    (decf (animal-energy animal))))

(defun turn (animal)
  (let ((x (random (apply #'+ (animal-genes animal)))))
    (labels ((angle (genes x)
               (let ((xnu (- x (car genes))))
                 (if (< xnu 0)
                     0
                     (1+ (angle (cdr genes) xnu))))))
        (setf (animal-dir animal)
              (mod (+ (animal-dir animal) (angle (animal-genes animal) x)) 8)))))

(defun eat (animal)
  (let ((pos (cons (animal-x animal) (animal-y animal))))
    (when (gethash pos *plants*)
      (incf (animal-energy animal) *plant-energy*)
      (remhash pos *plants*))))

(defparameter *reproduction-energy* 201)

(defun reproduce (animal)
  (let ((e (animal-energy animal)))
    (when (> e *reproduction-energy*)
      (setf (animal-energy animal) (ash e -1))
      (let ((animal-nu (copy-structure animal))
            (genes     (copy-list (animal-genes animal)))
            (mutation  (random 8)))
        (setf (nth mutation genes) (max 1 (+ (nth mutation genes) (random 3) -1)))
        (setf (animal-genes animal-nu) genes)
        (push animal-nu *animals*)))))

(defun update-world ()
  (setf *animals* (remove-if (lambda (animal)
                                 (<= (animal-energy animal) 0))
                             *animals*))
  (mapc (lambda (animal)
          (turn animal)
          (move animal)
          (eat animal)
          (reproduce animal))
        *animals*)
  (add-plants))

;; Parenscript's loop handling assumes that there's a from before a below
;; in ps-loop.lisp
;; It would be nice to fix this - sbcl has no problem with it, and the
;; The ANSI standard includes examples like this, e.g.
;; https://github.com/sbcl/ansi-cl-tests/blob/a755e2480caed1d3010943a9fbcfe61155a9240f/loop1.lsp#L185
;; (loop for x below 5 collect x) ; => (0 1 2 3 4)
;; I'd need to update PARENSCRIPT::for-clause and/or PARENSCRIPT::for-from
;; For now, though, I'm just going to make parenscript happy
(defun draw-world ()
  (loop for y
        from 0
        below *height*
        do (progn (fresh-line)
                  (princ "|")
                  (loop for x
                        from 0
                        below *width*
                     do (princ (let ((animal (some (lambda (animal)
                                                 (and (= (animal-x animal) x)
                                                      (= (animal-y animal) y)))
                                                   *animals*)))
                                 (cond (animal (char-for animal)) ;; Changed from #\M
                                       ((gethash (cons x y) *plants*) #\.) ;; changed from *
                                       (t #\space)))))
                  (princ "|"))))

(defun evolution ()
  (draw-world)
  (fresh-line)
  (let ((str (read-line)))
    (cond ((equal str "quit") ())
          (t (let ((x (parse-integer str :junk-allowed t)))
               (if x
                   (loop for i
                        from 0
                      below x
                      do (update-world)
                      if (zerop (mod i 1000))
                      do (princ #\.))
                   (update-world))
               (evolution))))))