;
; uLisp Animals Game
; see http://www.ulisp.com/show?1LKX
;

(defvar *data* '("Does it live in the sea?" "a dolphin" "a horse"))

(defun run (tree)
  (if (listp tree)
      (ask tree)
    (try tree)))

(defun yes-no ()
  (eq (read) 'y))

(defun printlist (&rest lst)
  (terpri)
  (mapc princ lst))

(defun ask (tree)
  (printlist (first tree) " ")
  (if (yes-no)
      (list (first tree) (run (second tree)) (third tree))
    (list (first tree) (second tree) (run (third tree)))))

(defun try (animal)
  (printlist "Is it " animal "? ")
  (cond
   ((yes-no) (printlist "Ho ho!") animal)
   (t (printlist "What were you thinking of? ")
      (add animal (read-line)))))

(defun add (animal new)
  (printlist "Give me a yes/no question to distinguish between " new " and " animal ": ")
  (let ((question (read-line)))
    (printlist "What would the answer be for " new "? ")
    (if (yes-no)
        (list question new animal)
      (list question animal new))))

(defun go ()
  (setq *data* (run *data*))
  nil)