Lesson 1, Common Lisp

Language: Layout:

;gnu clisp  2.49.60

;Basics to know about lisp: 
; 1) it is prefix notation -> (function-name argument) -> (+ 2 4) -> Evaluate -> Result: 6
; '(print 1) -> nothing will happen because the apostrophee means " no evbaluation"

(print (list 1 2 3 4))

(let* ((x 1) ;we basically start off by binding the value of 1 to "x". 
         (y (+ x 1))) ; The "let" function allows the initial value of 1=x be added to 1 and hence allow "2" to be binded to variable y. 
(print (list y x))) ; the "print" function allows for the list containg "y" and "x" to be printed.

;Tutorial: problem #1
; Write the following expression in Lisp: 2 * cos 0 * (4+6)

;Solution:

(print(* 2 (cos 0)(+ 4 6))) ; the function used in here is the "multiplication" which takes in 3 arguments in this case.

;problem #2
; Write the following expression in Lisp: not ((1+2=3) and (4<3) and (2+3=7))

(=(+ 2 3)7)

(print(not(and(=(+ 2 3)7)(< 4 3)(=(+ 1 2)3))))

;problem #3
;Set a variable PETS equal to DOG and CAT

(setq PETS '(dog cat)) ; basically setting pets equal to what is asked. 
(print PETS)

;problem #4
; Construct a list using the keyword "cons" (refer back to figure in tutorial slides)

(print(append '(1 2 3) '(a b c) '((1 4 5)))) ; append can onling accept list as a paramter, A typical append function will look like this : (append list#1 list#2 list#3 ....)

(print(list 1 '(b) 'a '(a h 7) '8 '((1 2 4)))); typical list function will look like this: (list element element element ..)

(print(cons '(3) '(4) )) ; the "construct method only expects two parameters: (cons element list)

; Remeber to work backwards, start off with the last "cons cell" and work you way backwards

; we know that the cons function looks something like this (cons element list)

;Answer:

(print(cons 'a (cons (cons'b (cons'c ()))()))) ; this function is behaves like linked lists where the second parameter basically points to the next cell.

;problem #5

(print(cons(cons'a(cons'b(cons(cons'c(cons 'd'()))'())))'()))

;conditional expressions

;(if (condition) 
    
    ;(answer 1)
    ;(answer 2) )

(if (= 0 0)
    (print 1)
    (print 2)) ;since condition is satisfied the answer that will be printed is 1.

;Defining new functions in LISP

; (defun name(parameters)
           ; (body))

(defun test(a b)
    
    (if (< a b)
        (print a)
        (print b)))

(test 5 6)

;Problem #6

;Define a function that will return two times the value of its input argument "x".

(defun test2(x)
    
    (print(* 2 x )))

(test2 5)

;Continue remaining problems

[ + ] Show input
Absolute running time: 0.17 sec, cpu time: 0.03 sec, memory peak: 7 Mb, absolute service time: 0,34 sec