;;;;More abour parameters
;Adam Nelson
;Chet Tobrey

(setf (symbol-function 'find-all-if) #'remove-if-not)

;;;; this function is defined in the version of ANSI Common Lisp we are using;;;;
#|(defun complement (fn)
  "if FN returns y, then (complement FN) returns (not y)"
  #'(lambda (&rest args) (not (apply fn args))))|#

(defun find-all (item sequence &rest keyword-args
                 &key (test #'eql) test-not &allow-other-keys)
  "Find all those elements of sequence that match item
  according to the keywords. Doesn't alter sequence."
  (if test-not
      (apply #'remove item sequence
             :test-not (complement test-not) keyword-args)
      (apply #'remove item sequence
             :test (complement test) keyword-args)))



(egs :3.19
     (eg '(defun math-quiz (op range n)
           "Ask the user a series of math problems."
           (dotimes (i n)
             (problem (random range) op (random range))))
     :of "defining the naive math-quiz"
     :out 'MATH-QUIZ)
     (eg '(defun problem (x op y)
           "Ask a math problem, read reply, and say if correct"
           (format t "~&How Much is ~d ~a ~d?" x op y)
           (if (eql (read) (funcall op x y))
               (princ "Correct!")
               (princ "Sorry incorrect :(")))
         :of "problem function used in math quiz"
         :out 'PROBLEM)
     (eg '(math-quiz '+ 100 2)
         :of "math quiz in use")
     (eg '(defun math-quiz-two (&optional (op '+)(range 100)(n 2))
           "asks the user a series of math problems"
           (dotimes (i n)
             (problem (random range) op (random range))))
         :of "same function but with optional parameters. default values are specified if no params are given")
     (eg '(math-quiz-two)
         :of "math quiz two")
     (eg '(defun math-quiz-three (&key (op '+)(range 100)(n 2))
           "Math quiz"
           (dotimes (i n)
             (problem (random range) op (random range))))
         :of "the &key argument allows us to specify arguments.&key, &optional, and &rest are called lambda-list keywords.")
     (eg '(math-quiz-three :op '-)
         :of "using :op '-")
     (eg '(defun times-two (&xyz)
           (+ &xyz &xyz))
         :of "& has no significance and is treated as a symbol."
         :out 'TIMES-TWO)
     (eg '(times-two  3)
         :of "using f"
         :out '6)
     (eg '(defun g (&key x y)(list x y))
         :of "function g"
         :out 'G)
     (eg '(let ((keys '(:x :y :z)))
           (g (second keys) 1 (first keys)2))
         :of "specifying the keys and where they will end up in the list"
         :out '(2 1))
     (eg '(find 3 '(1 2 3 4 -5 6.0))
         :of "find looks for a particular element in a sequence"
         :out '3)
     (eg '(find 6 '(1 2 3 4 -5 6.0))
         :of "looking for 6"
         :out '6)
     (eg '(find 6 '(1 2 3 4 -5 6.0) :test #'equalp)
         :of "find takes several keyword arguments. if none is specified it tests with eql. here we use equalp"
         :out '6.0)
     (eg '(setf nums '(1 2 3 2 1))
         :of "sets nums to the list (1 2 3 2 1)"
         :out '(1 2 3 2 1))
     (eg '(find-all 1 nums :test #'=)
         :of "checks all of the numbers in the list to a value of 1"
         :out '(1 1))
     (eg '(find-all 1 nums :test #'= :key #'abs)
         :of "removing 1's"
         :out '(1 1))
     )