;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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;;	CPSC 625 and 420
;;
;;	Exercises: Some (rather) random Lisp expressions
;;
;;	Yoonsuck Choe 
;;	http://faculty.cs.tamu.edu
;;	Thu Sep  2 10:52:37 CDT 2004
;;
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;



; various list operations

(car '(a (b c)))
(car '((b c) a))
(cdr '(a (b c)))
(cdr '((b c) a))


; various list operations

(cadr '(a (b c)))
(list 'a '(1 2) '((3 5) (7 8)))
(length '(a b c))
(first '(a b)) 
(nth 2 '(a b c d))


; various list operations

(cons 'a '(1 2 3))
(cons '(a) '(1 2 3))


; assignment

(setq x 10)
x



; assignment

(setq a (make-array '(3 3)))
(aref a 2 2)
(setf (aref a 2 2) 1000)
(setq (aref a 2 2) 1000)


; assignment (into address)

(setf b '(1 (2 3) 4))
(caadr b)
(setf (caadr b) 'abcdefg)
b


; arithmetic

(+ (* 2 3) (/ 4 5))



; function

(defun mult (x y) 
    (* x y) 
)

(defun mult (x y)
    (let ((tx x) (ty y))
        (* tx ty)
    )
)

; recursion

(defun fibo (x)
  (cond 
     ((equal x 1) 1)
     ((equal x 2) 2)
     ((> x 2) 
          (+ (fibo (- x 1)) (fibo (- x 2))))
  )
)


(defun fibo (x)
  (print (format nil "Entering fibo(~d)~%" x))
  (cond
     ((equal x 1) 1)
     ((equal x 2) 2)
     ((> x 2) 
          (+ (fibo (- x 1)) (fibo (- x 2))))
  )
)
   

; local context

(let ((a 3)) (+ a 1))

(let ((a 2) 
      (b 3)
      (c 0))
     (setq c (+ a b))
     c
)

(setq c 4)
(let ((c 5)) c)
c



; lexical scope

(setq ext:*top-level-auto-declare* nil)
(setq regular 5)
(defun check-regular () regular)
(check-regular)
(let ((regular 6)) (check-regular))




; dynamic scope

(defvar *special* 5)
(defun check-special () *special*)
(check-special)
(let ((*special* 6)) (check-special))
*special*
(let ((x 23)) (check-special))



; blocks

(progn
      (setq a 123)
      (* 5 10)
) 


; errorneous block

(
    (setq x 10)
    (setq y 20)
    (* x y)
)


; conditionals 

(if (> 2 3)     ; condition
      (+ 4 5) ; when true
      (* 4 5) ; when false
)

(defun compare-it (x)
  (cond 
	((eq x 1) (* x x))
	((eq x 2) (+ x x))
	((eq x 3) (/ x 2))
	(T      0)
  )
)

(compare-it 1)
(compare-it 2)
(compare-it 3)
(compare-it 50)

(numberp 10)

(zerop 2)

(atom 'x)

(atom '(1 2 3))


; loops

(dotimes (k 10 val) (setq val k))


; formatted output

(format t "Hello, world!")

(format nil "Hello, world!")

(format 
      nil
      "One: ~d~%Two:~f~%Three:~5,2f"
       12 (/ 4 3) (/ 4 3)
)